Israel announced Thursday it would not free an expected fourth, and final, batch of Palestinian prisoners. The government said this was a response to a push by the Palestinian Authority for more recognition at the United Nations.

The prisoner release was one promise made by Israel as part of the deal negotiated last August that restarted US-led Middle East peace talks. In return, Palestinian authorities agreed to suspend their membership application to UN agencies.

Palestinian President Mahmoud Abbas said the move on Wednesday to seek to join 15 international conventions through the UN was a response to Israel's failure to release the prisoners as promised at the end of March.

A statement from Israel's chief negotiator Tzipi Livni, sent to The Associated Press, said the Palestinians' decision violated the terms set for the prisoners' release.

US Secretary of State John Kerry, who has led the negotiations, spoke earlier on Thursday during a visit to Algeria, calling it a "critical moment" for the peace process.

"You can facilitate, you can push, you can nudge, but the parties themselves have to make fundamental decisions to compromise," Kerry said in Algiers. "The leaders have to lead, and they have to see a moment when it's there," he added.

White House spokesman Jay Carney said Thursday that Israel's decision has posed a roadblock to peace efforts.

"The decision by the Israelis to delay the release of the fourth tranche of prisoners creates challenges," he said.

hc/msh (AFP, Reuters)