Palestinian President Mahmoud Abbas dispatched top aides to Washington on Sunday to try to narrow differences with Israel and ensure wide Arab participation in a U.S.-led peace conference.

Abbas and Israeli Prime Minister Ehud Olmert plan to meet on Monday in Jerusalem for the last time before attending the conference on Palestinian statehood, which senior officials expect to convene in Annapolis, Maryland, on Nov. 26-27.

The U.S. government has been pressing Israel to go beyond a suggested partial West Bank settlement freeze and to increase the number of Palestinian prisoners it has offered to release before the conference, Israeli and Western officials said.

Preparations have also been marred by disputes over a joint document meant to address in general terms issues such as borders, and the future of Jerusalem and Palestinian refugees.

U.S. and Israeli officials have said a joint document is not a precondition for holding the Annapolis conference on schedule. They stressed the centrepiece of the gathering would instead be an agreement to resume formal statehood negotiations.

Palestinian officials suggested reaching an agreement on the joint document was key to ensuring the participation of key Arab states such as Saudi Arabia.

Abbas sent a team led by Yasser Abed Rabbo to Washington ahead of a meeting of Arab League foreign ministers on Thursday. Palestinian officials said Arab states would decide then whether to attend the conference.

U.S. President George W. Bush called for the conference to bolster Abbas and the long-stalled peace process after Hamas Islamists seized the Gaza Strip in June. The Bush administration may also be seeking to boost its own legacy after the Iraq war.

In addition to at least a partial freeze in Jewish settlement building in the occupied West Bank, Olmert plans to ask his cabinet on Monday to approve the release of up to 450 Palestinian prisoners, short of the 2,000 requested by Abbas, Israeli officials said.

A 2003 peace "road map" calls on Israel to freeze settlement activity and for the Palestinians to rein in militants.

Palestinians say they have started taking stronger steps against gunmen. Abbas's forces on Sunday entered a refugee camp near the West Bank city of Nablus, surrounding homes where they believed suspected militants were holed up, sparking a standoff.

TORTURED THOUGHTS

Looking ahead to peace moves, Olmert said in a speech he was haunted by "tortured thoughts" late at night as he weighed up "how to act and what to decide".

"Annapolis cannot be a failure because it is already a success just for taking place," Olmert was quoted earlier as telling French Foreign Minister Bernard Kouchner. "It is a launching of talks which have not taken place in seven years in the presence of dozens of countries and the entire world."

British Foreign Secretary David Miliband, also visiting the region as European powers rally behind the American push for peace, said: "This is a real moment of opportunity ... These opportunities don't come along very often ... The leadership in Israel and the Palestinian territories have shown vision."

Olmert had sought to exempt the occupied West Bank's major settlement blocs, which Israel aims to keep under any final peace deal, from any construction freeze. But Washington rebuffed the idea, Israeli and Western officials said.

The Palestinians say they will accept nothing short of a total freeze in settlement activity, including "natural growth" of existing settlements, as called for under the road map.

Some 270,000 Jewish settlers live in the West Bank among 2.5 million Palestinians. The World Court has branded illegal all settlements on land captured by Israel in the 1967 war. (Additional reporting by Jeffrey Heller, Avida Landau and Alastair Macdonald in Jerusalem; Writing by Adam Entous; Editing by Michael Winfrey)