Israel this week gave preliminary approval for 800 new settler homes in the occupied West Bank, put on the market plots for 1,200 more and were set to lay the cornerstone for a new settlement neighborhood consisting of scores of homes in occupied East Jerusalem.
Speaking to Reuters at his office in the desert city of Jericho, near the border with Jordan, Erekat warned that Palestinian patience with the settlements was limited.
"Those who do these things are determined to undermine the peace negotiations, are determined to force people like us to leave the negotiating table," he said in an interview
"If the Israeli government believes that every week they're going to cross a red line by settlement activity, if they go with this behavior, what they're advertising is the unsustainability of the negotiations," he added.
After six rounds of shuttle diplomacy, U.S. Secretary of State John Kerry coaxed Erekat and his Israeli counterpart Tzipi Livni into their first official talks in Washington last month after a three-year hiatus caused by disputes over settlements.
Around half a million Israeli settlers live in East Jerusalem and the West Bank, land captured by Israel in the 1967 Six Day War which Palestinians want as part of a future state.
The settlers and the Israeli prime minister's right-wing base are reluctant to quit the land where they cite Biblical and historical roots, but Palestinians say the settlements end the last chance for a viable state of Palestine.
"We are determined to give this effort of six to nine months every chance it deserves ... it's time for the Israeli government to choose negotiations and show good faith," he said.
PRISONERS, PRECONDITIONS
The talks have had a shaky start, as Erekat and Netanyahu both submitted letters to Kerry on Saturday complaining that the other side's actions harmed progress.
Erekat cited settlements while Netanyahu accused the Palestinians of "incitement" and "hate education" after Mahmoud Abbas said last month that he wanted no Israeli soldiers or civilians to live in a future Palestine.
Erekat welcomed Israel's decision to release 104 Arab prisoners in four phases, with the first 26 expected to be freed on Tuesday.
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Israel has publicly ruled out any preliminary deals on borders and settlements, calling them preconditions on issues that must be agreed at the end, not the start, of negotiations.
Speaking to reporters in Cairo last month, Palestinian President Mahmoud Abbas said talks would focus first on borders and security, which would appear to address their old demands.
"It's time for decisions, not negotiations," Erekat said, "and I hope Palestinians and Israelis will be able to make the decisions required to reach a comprehensive agreement on all core issues without exception, meaning Jerusalem, borders, settlements, refugees, water and security."