RAMALLAH, West Bank — US envoy George Mitchell met Palestinian president Mahmud Abbas on Friday to push Middle East peace efforts despite President Barack Obama's admission that his drive for a deal may have been overambitious.

Mitchell's talks in Ramallah, the political capital of the occupied West Bank, came a day after meetings with the Israeli government and talks in Syria and Lebanon, two countries the envoy said should play a key role in achieving a comprehensive Middle East peace deal.

But there were no expectations of a breakthrough as Israel and the Palestinians sparred anew and the US president acknowledged the scale of the difficulties.

"This is as intractable a problem as you get," Obama said in an interview published in Time Magazine's latest issue.

Both the Israelis and the Palestinians have found that "the political environment, the nature of their coalitions or the divisions within their societies, were such that it was very hard for them to start engaging in a meaningful conversation," Obama said.

"I think it is absolutely true that we... didn't produce the kind of breakthrough that we wanted," he said, adding that if his administration had anticipated the political problems on both sides, "we might not have raised expectations as high."

Washington had pressed hard for Israel to freeze settlement construction, which Abbas says is a precondition for negotiations to resume after a hiatus of more than a year.

Hawkish Israeli Prime Minister Benjamin Netanyahu announced in November a 10-month moratorium on issuing construction permits for Israeli homes in the West Bank outside annexed Arab east Jerusalem, but the Palestinians said this fell far short of their demands.

On Thursday, UN chief Ban Ki-moon noted with concern that, despite Israel's decision to restrain some settlement construction in the West Bank, "activity and financial support for expansion are continuing there and in east Jerusalem."

"Settlement construction violates international law and contravenes the roadmap, under which Israel is obliged to freeze all settlement activity," he said.

He also stressed the need for both sides to resume negotiations. "If we do not move forward on the political process soon, we risk sliding backwards."

The Israeli premier further complicated the task facing Mitchell on Wednesday by laying down a new precondition for any peace deal.

Netanyahu insisted that Israel would keep a permanent presence in the Jordan Valley on the eastern border of the Palestinians' promised state.

The Palestinians categorically rejected the suggestion.

Israel's Haaretz newspaper on Friday quoted a senior minister it did not name as saying the chances for a resumption of peace talks were "slim."

The mass-circulation Yediot Aharonot for its part said that Israeli officials believe the US administration will now put the Israeli-Palestinian issue at the bottom of its list of priorities.

"The administration will continue to try to renew negotiations, but will not go out of its way," it quoted an official it did not name as saying.