CAIRO, Dec 15 (Reuters) - The Arab League said on Wednesday there would be no resumption of negotiations between the Palestinians and Israel until the United States offered a serious proposal for ending the Middle East conflict.

U.S. Middle East envoy George Mitchell said earlier on Wednesday he would hold separate talks with the Israelis and Palestinians, whose face-to-face negotiations broke down in September over the issue of Israeli settlement building.

Arab League Secretary-General Amr Moussa said the body's peace process committee had decided not to resume negotiations until a serious proposal is made allowing for an end to Arab-Israeli conflict.

The Palestinians pulled out of the direct, U.S.-backed negotiations when Israel refused to extend a 10-month freeze on West Bank settlement construction which ended on Sept. 26.

The United States said last week it had been unable to persuade Israel to impose new restrictions on settlement building and it would resume indirect negotiations on the issues at the heart of the six-decade old conflict.

Moussa did not specify whether the Arab opposition to negotiations included the indirect talks.

The Palestinians say any resumption of face-to-face talks with Israeli Prime Minister Benjamin Netanyahu requires a full halt to construction on land where they aim to found a state, including a stop to Israeli building in East Jerusalem.

Officials meeting at the Arab League headquarters in Cairo on Wednesday were angered by the U.S. position as conveyed to them by Palestinian President Mahmoud Abbas, a senior Palestinian official who attended the meeting said.

A senior Palestinian official had said Abbas was going to the Arab League for recommendations on the Palestinians' next step. The Palestinian leadership would take decisions at a meeting of the Palestine Liberation Organisation's executive committee in the coming days, the official said.

Mitchell met both Abbas and Netanyahu this week.

The Palestinians asked Mitchell to come back to them with Israel's ideas on what the borders of the future Palestinian state would look like, a senior Palestinian official said, suggesting indirect peace talks are already underway.

Mitchell, who held talks with Moussa earlier on Wednesday, said both parties wanted Washington to continue to shepherd negotiations.

In the days ahead our discussions with both sides will be substantive one-way conversations with an eye on making real progress in the next few months on key questions of an eventual framework agreement, Mitchell told reporters.

But Qatari Prime Minister Sheikh Hamad bin Jassim al-Thani, chair of the Arab League committee, said he did he did not expect anything from the United States. In light of the talks with Mitchell, the American mediator has nothing new to offer, he said. (Reporting by Marwa Awad and Ayman Samir; editing by Philippa Fletcher and David Stamp)