Israeli Prime Minister Ariel Sharon warned his government would not tolerate the slightest Palestinian violation, citing European tolerance of Germany's Nazi regime in the 1930s as the root of World War Two.

The Palestinians meanwhile said it was Sharon's government that was failing to carry out the first steps required in the peace plan drawn up by the European Union, Russia, the United Nations and the United States.

"The experience of the past shows that the worst mistake, after reaching an agreement, is ignoring violations in implementation, even if they appear small," Sharon was quoted as saying by the Israeli press.

"We are at the beginning of the implementation of the first stage of the roadmap, which is based on a ceasefire and specific steps toward a total cessation of violence, terrorism and incitement," Sharon said.

"There is no progression from one phase to the next before the full implementation of the previous one," he said, implying that the Palestinian Authority yet had to deliver on its pledge to disarm militants.

The roadmap, which paves the way for the creation of a Palestinian state by 2005, calls on Palestinians to crack down on radical militants but also urges Israel to freeze Jewish settlement activity and dismantle settlement outposts.

But according to rights groups, more such outposts have been built than evacuated since the roadmap was launched, while on Thursday Israel announced that it was seeking to build more homes in a Gaza Strip settlement.

On Thursday night, the Palestinians called for urgent action from the sponsors of the political process to decide on their response to "the escalation of Israeli actions."

Nabil Abu Rudeina, a top aide of Yasser Arafat, spoke after a meeting of the combined Palestinian leadership, including both the Palestinian leader and his moderate premier Mahmud Abbas, who had previously been at odds over policy towards the peace process.

The appeal to the international community, reminiscent of the statements issued almost daily by Arafat's office before the roadmap was published, reflected Palestinian frustration at the failure of Abbas' talks last week in Washington to yield any significant Israeli concessions.

The Palestinians had hoped to obtain increased US pressure on Israel after US President George W. Bush criticised the separation barrier Sharon's government is erecting in the West Bank.

But the Israeli premier returned Thursday from his own trip to the White House after cordial talks with Bush and promised to continue the construction of the controversial fence.

And the US State Department said the freeze on settlement activity mandated by the roadmap, including what the Israelis call "natural growth", was still under discussion.