Amit showed me a copy of those rules at our first meeting. After two years of training in the Mossad academy at Herzlia near Tel Aviv, each recruit to the kidon is given a copy.

The killing in Dubai is a classic example of how Mossad goes about its work. Al-Mabhouh's 11 assassins had been chosen from the 48 current kidon, six of whom are women.

It has yet to be established how al-Mabhouh was killed, but kidon's preference is strangling with wire, a well-placed car bomb, an electric shock or one of the poisons created by Mossad scientists at their headquarters in a Tel Aviv suburb.

The plan to assassinate Mahmoud al-Mabhouh had been finalised in a small conference room next to the office of Meir Dagan, who has run Mossad for the past eight years. The 10th director-general, Dagan has a reputation as a man who would not hesitate to walk into a nameless Arab alley with no more than a handgun in his pocket.

Only he knows how many times he has asked a prime minister for legal permission to kill a terrorist who could not be brought to trial in an Israeli court, along with the kidon to whom he shows the legally stamped document, the licence to kill.

Mahmoud al-Mabhouh's name had been on such a document, which would have been signed by Benyamin Netanyahu. That, like every aspect of a kidon operation, would be firmly denied by a government spokesman, were he to be asked. This has not stopped Dubai's police chief, Lt-General Tamin, from fulminating against the Israeli prime minister.

Two years ago this week, Dagan sent a team of kidon to Damascus to assassinate Imad Mughniyeh. His Mossad file included details of organising the kidnapping of Terry Waite and the bombing of the US Marine base near Beirut airport, killing 241 people. The United States had placed a £12.5 million bounty on his head. Dagan just wanted him dead.

Mossad psychiatrists, psychologists, behavioural scientists, psychoanalysts and profilers – collectively known as the "specialists" – were told to decide the best way to kill Mughniyeh.

They concluded that he would be among the guests of honour at the Iranian Cultural Centre celebrations in 2008 for the celebration of the Khomeini Revolution. The team rigged a car-bomb in the headrest of the Mitsubishi Pajero they discovered Mughniyeh had rented, to be detonated by a mobile phone. As Mughniyeh arrived outside the Culture Centre at precisely 7pm on February 12, the blast blew his head off.

At Mughniyeh's funeral in Beirut, his mother, Um-Imad, sat among a sea of black chadors, a sombre old woman, who wailed that her son had planned to visit her on the day after he died. She cried out she had no photograph to remember him by. Two days later she received a packet. Inside was his photograph. It had been posted in Haifa.

The list of kidon assassinations is long and stretches far beyond the Arab world. In their base deep in the Negev Desert – the sand broken only by a distant view of Israel's nuclear facility at Dimona – the kidon practise with a variety of handguns, learn how to conceal bombs, administer a lethal injection in a crowd and make a killing look accidental.

They review famous assassinations – the shooting of John F Kennedy, for example – and study the faces and habits of potential targets whose details are stored on their highly restricted computers. There, too, are thousands of constantly updated street plans downloaded from Google Earth.

Mossad is one of the world's smallest intelligence services. But it has a back-up system no other outfit can match. The system is known as sayanim, a derivative of the Hebrew word lesayeah, meaning to help.

There are tens of thousands of these "helpers". Each has been carefully recruited, sometimes by katsas, Mossad's field agents. Others have been asked to become helpers by other members of the secret group.

Created by Meir Amit, the role of the sayanim is a striking example of the cohesiveness of the world Jewish community. In practical terms, a sayan who runs a car rental agency will provide a kidon with a vehicle on a no-questions basis. An estate agent sayan will provide a building for surveillance. A bank manager sayan will provide funds at any time of day or night, and a sayan doctor provides medical assistance.

Any of these helpers could have been involved in the assassination of Mahmoud al-Mabhouh. Mossad has recently expanded its network of sayanim into Arab countries.

A sayan doctor in the West Bank provided details of the homoeopathic concoction Yasser Arafat used to drink. When he died in 2004, his personal physician, Dr al-Kurdi, said "poisoning is a strong possibility in this case".There have been reports that more than a dozen terrorists have died from poisoning in the past five years,.

Within the global intelligence community, respect for Mossad grew following the kidon assassination of Dr Gerald Bull, the Canadian scientist who was probably the world's greatest expert on gun-barrel ballistics. Israel had made several attempts to buy his expertise. Each time, Bull had made clear his dislike for the Jewish state.

Instead he had offered his services to Saddam Hussein, to build a super-gun capable of launching shells containing nuclear, chemical or biological warheads directly from Iraq into Israel. Saddam had ordered three of the weapons at a cost of $20 million. Bull was retained as a consultant for a fee of $1 million.

On the afternoon of March 20, 1990, the sanction to kill Bull was given by the then prime minister, Yitzhak Shamir. Nahum Admoni, the head of Mossad, sent a three-man team to Brussels, where Bull lived in a luxury apartment block. Each kidon carried a handgun in a holster under his jacket.

When the 61-year-old Bull answered the doorbell of his home, he was shot five times in the head and the neck, each kidon firing their 7.65 pistol in turn, leaving Bull dead on his doorstep. An hour later they were out of the country on a flight to Tel Aviv.

Within hours, Mossad's own department of psychological warfare had arranged with sayanim in the European media to leak stories that Bull had been shot by Saddam's hit squad because he had planned to renege on their deal.

The same tactics had been placed on stand-by on October 24, 1995, for the assassination of Fathi Shkaki who, like Mahmoud al-Mabhouh, had reached the top of Mossad's target list as a result of his terrorist attacks.

Two kidon – code-named Gil and Ran – had left Tel Aviv on separate flights. Ran flew to Athens, Gil to Rome. At each airport they collected new British passports from a local sayan. The two men arrived in Malta on a late-afternoon flight and checked into the Diplomat Hotel overlooking Valetta harbour.

That evening, a sayan delivered a motorcycle to Ran. He told hotel staff that he planned to use it to tour the island. At the same time, a freighter that had sailed the previous day from Haifa bound for Italy radioed to the Maltese harbour authorities that it had developed engine trouble. While it was fixed, it would drop anchor off the island. On board the boat was a small team of Mossad communications technicians. They established a link with a radio in Gil's suitcase.

Shkaki had arrived by ferry from Tripoli, Libya, where he had been discussing with Colonel Gadaffi what Mossad was convinced was a terrorist attack. The two kidon waited for him to stroll along the waterfront. Ran and Gil drove up on the motorcycle and Gil shot Fathi Shkaki six times in the head. It had become a kidon signature.

When the police came to search Shkaki's bedroom they found a "Do not disturb" sign on his door – a signature that was repeated in last month's Dubai killing.

Gordon Thomas is the author of 'Gideon's Spies'.

But Meir Dagan, the Mossad chief who stepped aside this month, insisted that with so many visitors from those three countries travelling to Dubai, their passports would not be scrutinised. After the Dubai debacle, the source said, Mr Pardo warned Dagan that the "whole business will come home to haunt us".

Mr Pardo, known as "T" to fellow Mossad officers since he joined the service 30 years ago, is said to regard the expulsion of the service's top official in London as a blow to the organisation. Since then official collaboration between Mossad and the British agencies responsible for security at home and abroad, MI5 and MI6, has been badly dented, to the detriment of both.

But Mr Dagan bluntly refused to apologise over the use of the faked passports – let alone offer the guarantee demanded by Britain that the theft would not recur.

Mr Pardo's apology and pledge during a visit to London that is expected early in January would be the first official acknowledgement by Israel that it was behind the assassination of the Hamas leader in Dubai.

He is expected to brief officials on Mossad's plans to provide Britain and Nato with increased intelligence over Iran's nuclear weapons programme. Mossad has a network of undercover agents in the country.

He also intends to increase Mossad's role in Yemen and to spearhead the hunt for al-Qaeda's new chief of military operations, Saif al-Adel, who Mossad believe is based in Somalia.

At the same time he wants to expand Mossad's watch over the SVR, Russia's foreign intelligence service, which is an increasing presence in Syria and Turkey – and is using both countries as launch pads from which to enter Europe. In his first briefing to senior staff after he took up his new post, Mr Pardo said Mossad had a key role to play in helping the West win what he called "the new Cold War".

He wants to persuade Britain's intelligence chiefs – Sir John Sawers, the head of MI6 and Jonathan Evans, the MI5 director – that it is now essential for the relationship with Mossad to be rebuilt. Sir John and he are said by insiders to have had an exploratory telephone conversation soon after the new Mossad chief took up his new job.

He has already made his first move to mend fences by deploying Mossad's powerful facial recognition technology to assist in solving the mystery of the death of MI6 codebreaker Gareth Williams, whose body was discovered in a padlocked bag in the bath of a flat in London.

The sophisticated system, known as Faces, is being used to sift through Mossad's vast database of faces to try to match e-fit images of the couple of Mediterranean appearance who Scotland Yard detectives believe had visited the flat in previous weeks. The Israeli agency believes the man is likely to be of Greek origin and the woman to have a Lebanese background.

Mr Pardo hopes to negotiate the return of a new station chief - the top Mossad post in London - who, because of Israel's normally friendly relations with Britain, would be formally "declared" to the Foreign Office as a Mossad officer working undercover as a diplomat at the Israeli embassy. The United States and some other countries deemed to be "friendly" have similar arrangements with the Foreign Office, which allows a spy to meet on a regular – and more open basis – Britain's own intelligence chiefs and senior government officers.

Ari Ben-Menashe, a former national security adviser to the Israeli government, has described "declared" positions as the plums among Mossad's foreign postings. "Socially, especially around Christmas, the station chief gets invites to every government party," he said. "The same with national holidays like Australia or Bastille days. A station chief has his membership for most of the exclusive clubs around Whitehall, and he gets to meet all sorts of interesting people."

Mr Pardo is himself an expert in telephone tapping and the discreet photographing of a target who has operated for Mossad all over the world.

He will brief British officials on how Mossad has placed deep cover agents in areas where MI6 cannot easily operate in Asia, Yemen and Iran. It has also established the strength of China's cyber war ability to attack the West. Mossad also has agents in Afghanistan tracking the Taliban.

Gordon Thomas is the author of Gideon's Spies, The Inside Story of Israel's Legendary Secret Service (JR Books)