Israeli and Palestinian negotiators met their US counterparts overnight Thursday to discuss ways to prevent the complete collapse of peace talks after both sides took steps Washington criticized as "unhelpful."

More than a year of shuttle diplomacy by US Secretary of State John Kerry was in jeopardy after Israel made a new bid to expand settlements in annexed Arab east Jerusalem and the Palestinians took fresh steps toward seeking recognition of their promised state.

White House deputy spokesman Josh Earnest expressed disappointment at "unhelpful, unilateral actions both parties have taken in recent days," but said Washington still believed diplomacy had a chance.

Ahead of the three-way talks, Kerry telephoned both Israeli Prime Minister Benjamin Netanyahu and Palestinian President Mahmoud Abbas to discuss the situation, a US official said.

There was no official word on the outcome of the meeting, which took place in Jerusalem and reportedly brought together US special envoy Martin Indyk with Israel's chief negotiator Tzipi Livni and her Palestinian counterpart, Saeb Erakat.

A source quoted by the Walla news website said chances of success were "slim, but we'll keep trying."

The standoff was triggered by Israel's refusal to release 26 Palestinian prisoners at the weekend, prompting the Palestinians to formally request accession to several international treaties in a bid to unilaterally further their statehood claim.

Each side accused the other of violating undertakings given when the current round of peace talks were launched in July under Kerry's sponsorship.

And the moves dealt a hammer blow to Kerry's frenetic efforts to broker an extension of the negotiations beyond their original April 29 deadline.

At the same time, the UN's special envoy on Mideast peace, Robert Serry, has received requests from Palestinian officials to join 13 international conventions and treaties, the UN confirmed Wednesday.

The treaties include the Vienna Convention on diplomatic relations, the convention on the rights of the child, the convention against torture, and the one against corruption.

Once these applications have been officially received at the UN headquarters, "we will be reviewing them to consider the appropriate next steps," said Farhan Haq, deputy spokesman for the secretary-general.

The requests come as peace talks between the Palestinians and Israelis were close to collapse, with Israel making a new bid to expand settlements in annexed Arab east Jerusalem and the Palestinians taking fresh steps towards seeking recognition of their promised state.

The Palestinians had pledged to freeze all moves to seek membership in UN organizations during the talks in return for Israel's release of the veteran Arab prisoners.

"We hope a way can be found to see the negotiations through," UN spokesman Haq said, noting that Serry had met with chief Palestinian negotiator Saeb Erekat and Israeli Justice Minister and chief negotiator Tzipi Livni.

AFP