JERUSALEM, April 13 (Reuters) - Israeli Prime Minister Ehud Olmert and Palestinian President Mahmoud Abbas held a surprise meeting on Sunday ahead of Abbas's visit to Washington for talks with U.S. President George W. Bush.

A senior Israeli official said the one-on-one meeting at Olmert's residence in Jerusalem, the second in a week, was brought forward to "increase the level of cooperation and coordination before Abbas visits Washington" this month.

Negotiations on issues at the heart of the Israeli-Palestinian conflict have shown little outward sign of progress since final-status talks were renewed at a U.S.-hosted peace conference in Annapolis, Maryland, last November.

The negotiations, led on the Israeli side by Foreign Minister Tzipi Livni and on the Palestinian side by Ahmed Qurie, have been bogged down by differences over Israeli settlement expansion and violence in the Hamas-controlled Gaza Strip.

Both sides are trying to meet a U.S. goal of a Palestinian statehood deal before Bush leaves office in January, but differences remain over what that accord might entail.

Abbas wants a full-blown agreement this year; Olmert says he wants to reach statehood "understandings" that would be implemented later.

Sunday's meeting came as a surprise because it was held so soon after the leaders met on April 7. This latest meeting had been expected to be held later in the week.

Abbas is expected to meet Bush at the White House on April 24, Palestinian officials said.

After last Monday's Abbas-Olmert talks, Abbas aide Saeb Erekat described differences over building in Jewish settlements, especially around Jerusalem, as "very deep".

But Israeli officials said the leaders agreed not to allow such issues to interrupt the U.S.-brokered negotiations.

Abbas last month briefly suspended the talks after an Israeli offensive killed more than 120 people in the Hamas-controlled Gaza Strip, where Palestinian militants have been firing rockets into Israel. (Reporting by Wafa Amr and Adam Entous, Writing by Adam Entous, Editing by Alison Williams)

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