The Palestinian leader has warned President Barack Obama that he will pull out of upcoming peace talks if Israel ends a slowdown of West Bank settlement construction, a Palestinian negotiator said Monday.

Direct negotiations aimed at ending the decades-old Mideast conflict are to resume in Washington next week after months of U.S. diplomatic efforts. Both sides seem pessimistic about the talks, their first in 20 months.

Israel's 10-month slowdown, which bans construction of new Jewish homes in the West Bank, is supposed to end in late September, and Israel's government is split over whether to extend it.

Head Palestinian negotiator Saeb Erekat said Palestinian President Mahmoud Abbas laid out his position in a letter to Obama and also sent copies to the European Union, the U.N. and Russia — all members of the Quartet of Mideast mediators.

"If Israel resumes settlement activities in the Palestinian territories, including east Jerusalem, we cannot continue negotiations," Erekat said, quoting from the letter.

The Palestinians seek an independent state in all of the West Bank, the Gaza Strip and east Jerusalem — territories Israel captured in the 1967 Mideast war. Israel withdrew settlers and soldiers from Gaza in 2005, but some 300,000 Jews still live in settlements around the West Bank. Another 180,000 live in areas of east Jerusalem the Palestinians want for their capital.

Israeli Prime Minister Benjamin Netanyahu opposes giving up Israeli control of east Jerusalem.

While Netanyahu strongly indicated last month that the West Bank slowdown would not be extended, the Israeli government is now signaling it might be flexible.

"The government has yet to announce officially what will be done. For the moment, the most important thing is to get the talks going, and we're not going to do anything to give the Palestinians an excuse to derail the talks," said Yigal Palmor, a spokesman for Israel's Foreign Ministry.

Netanyahu has not commented on the issue of the freeze since the U.S. announced on Friday that talks would be resuming in Washington next week. It will be the first face-to-face peace talks between the sides since late 2008. Obama hopes to forge a deal within one year.

Extending the settlement slowdown would be deeply unpopular among the more hawkish members of Netanyahu's coalition government and among many members of his own Likud party.

Some analysts have suggested that in order to press ahead with the talks the Israeli leader might be forced to rearrange his coalition, excluding some of the more hard-line parties and bringing in his more moderate rivals from the opposition Kadima party.