The White House press secretary, Ari Fleischer, delivered a public rebuke to Mr Powell for floating proposals that included creation of a "temporary" Palestinian state.

He accused Mr Powell of parroting the ideas of foreign government leaders rather than reaching his own conclusions.

Against a background of continuing violence in Israel and the occupied territories, Mr Bush is to make a speech within days that is meant to revive the peace process. But Mr Bush and Mr Powell are divided over the content.

Mr Bush is leaning heavily towards the Israeli prime minister, Ariel Sharon, who was returning to Israel yesterday after two days of talks in Washington. Mr Powell appears to be more sympathetic towards the Palestinian position.

Mr Sharon broke his flight home to stop in London to brief Tony Blair on the US visit. In an hour-long discussion at Downing Street, Mr Blair pressed him to re-engage in the political process rather than rely solely on military solutions, according to a Downing Street spokesman.

An Israeli government spokesman said Mr Sharon had been explicit about the "terror" that Israel faced and had told Mr Blair that "any kind of political talks will have to follow the end of terror".

Britain is encouraging Israel to drop its pre-conditions to entering the political process: an end to Palestinian attacks on Israelis and reform of the Palestinian Authority.

But there is no prospect of political negotiations without impetus being provided by Washington, which was yesterday in a state of paralysis.

Mr Powell, in an interview with a London-based Arab paper, al-Hayat, floated a series of ideas, including the creation of the "temporary" Palestinian state, a halfway house on the way to full statehood.

Mr Powell echoed Arab demands for "the end of the occupation" of the West Bank and Gaza by Israel, for "the creation of a state called Palestine" and for "the end of settlement activity".

He said that Mr Bush will announce "in the very near future" how he intends to secure a Palestinian state. Next Monday has been pencilled in for Mr Bush's speech but the timing could slip given the splits within the administration.

He said that Mr Bush had not ruled out setting a timetable for the creation of a Palestinian state. The Palestinians want the timetable but Mr Sharon is opposed.

Mr Powell also stressed the importance of holding an international conference, planned for this summer, to discuss the options for peace and, in contrast with Mr Bush and Mr Sharon, to continue to work with the Palestinian leader, Yasser Arafat.

"It's up to the Palestinian people to determine who their leader is, to determine who should head their government," Mr Powell said.

Hours after the interview was published, Mr Fleischer said Mr Powell's proposals would be treated as advice that Mr Bush may or may not heed.

Mr Fleischer said: "Welcome to the Middle East. This is a situation where people get a variety of information, a variety of advice and if the president has anything further to indicate, he will."

Mr Fleischer said the secretary of state was acting on advice he had heard from foreign leaders rather than stating his own conclusions. "The secretary, from time to time, will reflect on the advice that he gets and do so publicly, which is his prerogative."

Envoys from the Middle East "quartet" working on peace proposals are to meet in Washington tomorrow. The quartet is made up of the US, the UN, the EU, and Russia. The Saudi foreign minister, Prince Saud al-Faisal, alarmed at the extent to which Mr Sharon's voice rather than the Arab one is being listened to in the US administration, is to hold talks in Washington today.

Mr Sharon appears to be satisfied with assurances he received from Mr Bush about plans for the Middle East.