Israel's ambassador to Washington, Michael Oren, deemed U.S. special Mideast envoy George Mitchell's vision of peace within two years an "unrealistic goal".
Oren told The Washington Post in remarks published Monday that Mitchell's timetable "is unrealistic and might prove counterproductive."
"We know from our experience that state-making takes a long time," he added.
Oren's response came two days after Mitchell suggested that Barack Obama's administration was free to withhold loan guarantees from Israel should the latter delay the peace process any further.
Washington is now considering the possibility of launching "proximity talks" between Israel and the Palestinians, as Palestinian Authority President Mahmoud Abbas continues to object to direct talks.
Under this plan, Mitchell and his staff would meet separately with both parties, present each side's positions to the other and then try to bridge the gaps. This is the same system both George Bush Sr. and Bill Clinton used (unsuccessfully) for Israeli-Syrian talks.
Mitchell: Obama committed to comprehensive Mideast peace
Meanwhile, Mitchell on Monday reaffirmed Washington's support for a two-state solution to the Middle East crisis, and said a comprehensive regional peace was necessary for ending the Israeli-Palestinian conflict.
"A two-state solution is central to our peace efforts," Mitchell told journalists in Paris, after a meeting with French Foreign Minister Bernard Kouchner.
Mitchell added that Obama was committed to "a comprehensive peace in the Middle East," which included Israeli peace agreements with Syria and Lebanon as well as formal diplomatic ties between Israel and all its neighbors in the region.
Neither Mitchell nor Kouchner would comment on the present state of Middle East peace negotiations.
The former U.S. senator was in Paris ahead of a meeting of the international community's top negotiators on the Middle East in Brussels on Wednesday.
On Tuesday, Mitchell is to hold talks in Brussels with the European Union's newly-nominated foreign policy chief, Catherine Ashton, as well as the official Envoy of the Quartet on the Middle East, Tony Blair.
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