Condoleezza Rice gave a warning yesterday that progress would be slow as the US Secretary of State embarked on a round of shuttle diplomacy in the Middle East in advance of a peace conference next month.

Progress on a joint statement on Palestinian statehood, the framework of the US-hosted conference in Annapolis, Maryland, is still so limited that invitations have yet to be issued, and Dr Rice conceded yesterday that the coming days were unlikely to produce any significant breakthroughs.

Ehud Olmert, the Israeli Prime Minister, said that a joint statement was not a prerequisite for the conference, and is said to prefer a vague statement that will allow him to keep his fragile political coalition at home intact.

Palestinian negotiators have threatened to boycott the conference if a clear and defined statement, including timelines, is not set beforehand.

“Olmert is looking for a public relations conference and one that will allow normalisation with Arab countries,” Riad Malki, the Palestinian Foreign Minister, said. “We will not help him in this.”

Representatives from both sides have met regularly over the past few months. Talk of land swaps and Israel’s willingness to turn over much of Arab east Jerusalem to a future state of Palestine have contributed to a rare, if limited, optimism.

But progress has been slow, and news of the Israeli confiscation of Arab land between east Jerusalem and the settlement of Maale Adumim, has cast a shadow, prompting sharp demands for clarification from Dr Rice.

The “road map” for peace in the Middle East, as called for by the Quartet of mediators – the United Nations, European Union, United States and Russia – calls for a freeze on settlement activity.

She issued a measured warning to the Israelis as she arrived in Jerusalem: “We have to be very careful as we are trying to move toward the establishment of a Palestinian state about actions and statements that erode confidence in the parties’ commitment to a two-state solution.”

Officials say the land is needed for a bypass road, while Palestinians fear it will be used to expand settlements.

Dr Rice met Ehud Barak, the Israeli Defence Minister, yesterday and is expected to meet with leaders on both sides, before travelling to Cairo and London later this week.