The assurance comes shortly after measures were passed to allow the return of thousands of Serbs, for the first time since 1995, to the Krajina region, on the border with Serbia. The actions acknowledge that Croatia must come to terms with its past to join the European Union by 2007. The country’s relations with Europe have also become stronger in recent years, as evidence of alleged American involvement in the ruthless campaign to drive Serbs from the region has begun to emerge.

The President, a former dissident in Communist Yugoslavia, also said he was optimistic that recent measures introduced by the Government in Zagreb would allow more of the 200,000 Serbs driven from the Krajina region during the 1995 Croatian offensive to return to their homes.

Mr Mesic, 69, told The Times that Croatia was trying to facilitate the return of all refugees and their integration into Croatian society. “By doing so, Croatia is proving the maturity of its democracy.”

Only a few of the Serbs who fled Krajina in 1995 have returned; most are old and many have had difficulty reclaiming their homes from Croatians.

About 20,000 Croatians were killed during the war of independence, thousands of them at Vukovar, the Slavonian city whose siege, with that of the Adriatic seaport of Dubrovnik, symbolised the heroism of Croatian fighters facing the combined strength of the Yugoslav army and Serb paramilitary forces.

International attention initially focused mainly on atrocities against Croatians, such as the slaughter of hundreds of wounded soldiers who were taken from the hospital at Vukovar and shot after the town fell.

But recently the indictments of Croatian commanders by the International Criminal Tribunal for the Former Yugoslavia for alleged crimes against Serbs have provoked nationalist support for men still seen as heroes, and a surge in support for Franjo Tudjman’s Croatian Democratic Party.

Mr Mesic welcomes co-operation with the tribunal. Croatia, however, cannot arrest the most wanted Croatian, General Ante Gotovina, because he is hiding in neighbouring Bosnia. General Gotovina was charged by the tribunal last year with responsibility for the murder and disappearance of hundreds of Serb civilians after the Croatian offensive in Krajina, and for the expulsion of Serb civilians to Bosnia and Yugoslavia.

Western diplomats say that Croatia has made efforts to arrest Gotovina but that nationalists in the intelligence agency protect him. He is also believed to be harboured by hardliners from the Croatian Church hierarchy.

Another major obstacle is American concern that if General Gotovina is arrested he may carry out a threat to disclose the previously unknown extent of US covert involvement in the Krajina offensive.