Last-ditch talks between Israeli and Palestinian negotiators on salvaging a teetering, US-brokered peace process ended without a breakthrough Sunday, Palestinian sources told AFP.

"The crisis continues. During the whole meeting, the Israelis threatened the Palestinians and no solution to the crisis was found," a Palestinian official said, speaking on condition of anonymity.

Warning that the peace process was on the edge of collapse, an Israeli official close to the talks said that even US Secretary of State John Kerry, its tireless sponsor, was cooling off.

"The way it's looking now, the talks as they were several weeks ago are no longer relevant," the source told Israeli news website Ynet.

"Israel is preparing to return to routine dealings with the Palestinians as they were before the negotiations started nine months ago.

"We are noticing a real coolness in the way the Americans are treating [the peace process], and it's obvious that today's Kerry is not the same Kerry from a few weeks ago," the official added.

A second official, however, said another chance needed to be given to the efforts of Israel's chief negotiator Tzipi Livni.

"We have to wait a few more days ... A lot of efforts are being done to salvage the situation," the official said.

Israeli Prime Minister Benjamin Netanyahu, meanwhile, threatened to retaliate if the Palestinians proceed with applications to adhere to 15 international treaties.

AFP