JERUSALEM (Reuters) -- Israeli President Shimon Peres came to the defense of Mahmoud Abbas on Tuesday after Israel's far-right foreign minister called the president an obstacle to peace.

"Abbas and Prime Minister (Salam) Fayyad are serious leaders that want peace and are working to prevent violence and extremism in our region," said Peres in public remarks.

"We must continue to negotiate peace with them in order to achieve full peace that will end this long conflict," he said in a meeting with "Seinfeld" actor Jason Alexander, a member of "One Voice", an international movement promoting a two-state solution.

Israeli Foreign Minister Avigdor Lieberman, who heads an ultra-nationalist party in the governing coalition, said in a briefing to reporters on Monday that Abbas was blocking any progress towards peace.

"If there is an obstacle that could be removed it's Abu Mazen," he said, calling on Abbas to resign.

"He threatens he will hand back the keys," Lieberman said, referring to the Western-backed Abbas's warnings in the past that he would quit unless a statehood deal could be achieved. "It's not a threat, it's a blessing."

There was no indication that Lieberman's fiery remarks reflected any change in Israeli government policy, and they elicited no response from Prime Minister Benjamin Netanyahu.

Netanyahu has called on Abbas to resume negotiations, which collapsed 13 months ago in a dispute over Israeli settlement building in the occupied West Bank, and abandon a unilateral bid for UN recognition of a Palestinian state.

Lieberman's remarks drew Palestinian anger and condemnation by a spokesman for UN Middle East envoy Robert Serry, and from European Union foreign policy chief Catherine Ashton, on the eve of a new push by international mediators for renewed talks.

Maja Kocijancic, a spokeswoman for Ashton, said on Tuesday Lieberman's remarks were "regrettably not helpful to create the environment of trust conducive to negotiations."

PLO official Saeb Erekat told Voice of Palestine Radio, "we consider this tantamount to a call for the physical assassination of (Abbas)."

"This is criminal incitement. We called the American administration, we sat with our friends in the Russian Federation and the European Union," Erekat said.

UN spokesman Richard Miron, meanwhile, called the comments "deeply troubling". Speaking for the UN's envoy in Jerusalem Robert Serry, Miron said the remarks seemed intended to "delegitimize" the president.

Criticizing Lieberman's "inflammatory remarks," Miron added that such statements "undermine trust at a time when the Quartet is working towards the resumption of negotiations."

Israeli and Palestinian negotiators were due to meet separately in Jerusalem on Wednesday with representatives of the Quartet of Middle East peace negotiators -- the United States, the European Union, the United Nations and Russia.

Expectations were low in Israel and the occupied territories that the indirect talks could lead to a resumption of face-to-face negotiations between the two sides.