Still, Abbas' surprise decision signaled a new crisis in Kerry's troubled peace efforts.
Kerry had nudged Israelis and Palestinians back to the table in July, after a five-year break in negotiations, and got them to commit to nine months of negotiations, until April 29. The target was to reach a framework deal on the terms of a Palestinian state alongside Israel.
As part of the resumption of talks, Abbas had promised to suspend efforts to seek further international recognition of a state of Palestine for nine months.
A major nod from the U.N. came in November 2012, when the General Assembly voted by an overwhelming majority to accept a Palestinian state in the West Bank, Gaza and east Jerusalem — lands Israel occupied in 1967 — as a non-member observer, overriding Israeli and U.S. objections.
Palestinian officials have said that vote paved the way for Palestine to join 63 international institutions, conventions and treaties. A Palestine Liberation Organization statement quoted Abbas as saying Tuesday that the 15 letters he signed were for conventions and treaties that can be joined immediately.
Israel, meanwhile, had pledged last year to release 104 of the longest-held Palestinian prisoners during the course of the negotiations. The Palestinians say the fourth and final group was to have been released by the end of March. Israel argues that the release was contingent on the Palestinians negotiating "in good faith."
In recent days, Kerry has been trying to negotiate a deal on extending the talks until the end of the year. An Israeli official close to the negotiations said earlier Tuesday that Kerry was pushing a formula that would include Pollard's release.
In exchange for Pollard, Israel would free the last group of 26 veteran Palestinian prisoners, show "restraint" in settlement building and release about 400 additional Palestinian prisoners it would select, the official said.