WASHINGTON (AFP) - The United States on Monday welcomed Israel's expected release of 26 Palestinian prisoners as Secretary of State John Kerry prepared to return to the region to hammer out a framework to guide fragile peace talks.

Mr Kerry "expresses his appreciation for Prime Minister (Benjamin) Netanyahu's decision to release the third tranche of prisoners", State Department deputy spokeswoman Marie Harf said.

"The Israeli government's commitment to release Palestinian prisoners helped enable the start... and the continuation of the final status negotiations, and we believe this is a positive step forward in the overall process," she added.

The prisoners were due to be released in the early hours of Tuesday. Mr Kerry is flying back to Israel on New Year's Day for his 10th trip to the country and the Palestinian territories since March.

During his talks with Mr Netanyahu and Palestinian leader Mahmud Abbas, the top diplomat will "discuss with both leaders the proposed framework for negotiations," Ms Harf said.

She added it would "serve as guidelines for the permanent status negotiation and would address all the core issues". She refused, however, to be drawn on reports that Israel was expected to accompany the releases with the announcement of new construction plans for Jewish settlements in the occupied West Bank and east Jerusalem.

The aim of the proposed framework was to help shape negotiations in the coming months as they work towards a full Israeli-Palestinian peace deal, Ms Harf said.

"If you start with nothing and you know all the issues are on the table, it makes sense to put some guidelines around the discussions of each of the final status issues to drive the process forward," she told reporters.

But she refused to go into details, other than to say it included all so-called core issues. These include the borders of a future Palestinian state, the fate of Jerusalem, the right of return of Palestinian refugees, security and what becomes of Jewish settlements.

Both sides agreed when the talks resumed in July after a three-year freeze that they would continue negotiating for the next nine months, and Ms Harf said Mr Kerry was still aiming for a final peace deal by that deadline.

"We know it's a complicated process, but we're still operating under that nine-month time frame," she added.