Katzav said that Hamas' refusal to denounce violence and to endorse past peace agreements would force Israel to take unilateral actions to secure peace.

“Israel wants to negotiate with the Palestinians to reach a final solution of the conflict,” Katzav told reporters in Sofia, Bulgaria, after meeting Georgi Parvanov, the Bulgarian president.

“But as long as Hamas continues to support terror, refuses to recognise Israel and defies commitments made by Yasser Arafat and Mahmoud Abbas, Israel has to find alternative ways to protect its citizens.”

Katzav said a plan by Ehud Olmert, the Israeli prime minister, for a partial withdrawal from the West Bank and unilaterally drawing Israel's border with the Palestinians was “a concept that is still being developed.”

Katzav was also critical of a move by Abbas, the Palestinian president, to schedule a referendum next month on the establishment of a Palestinian state alongside Israel, saying it would not help achieve peace.

“I doubt that this referendum would do anything to solve the tensions within the Palestinian society,” he said, adding that a solution to the Israeli-Palestinian conflict hinged on resolving internal battles between Abbas and Hamas.

“If the forces of reason led by Abbas win, peace will come soon,” Katzav said. “If destructive forces win, I am afraid tensions will escalate further.”

West Bank plan

Meanwhile Olmert, the Israeli prime minister, is in Europe trying to gather support for his plans for Israel and the West Bank.

Europe, the United States and several Arab states have pressed Olmert to try negotiations with Abbas before unilaterally setting the borders of Israel.

Olmert says he is ready to make painful concessions after withdrawing from parts of the West Bank.

“I am ready to make concessions that will be painful and divisive, the specific nature of which, the accurate aspect of all this will take place during the process of negotiations,” he said in an interview on Sky News.

Last year, Israel carried out a unilateral withdrawal from the Gaza Strip. But the partial West Bank pullout would fall short of Palestinian claims to all of the area for part of an independent state.

Olmert will meet Tony Blair, the British prime minister, in London and then flies to Paris for talks with Jacques Chirac, the French president.