* Minister says Abbas cheered Israelis on then changed tune
* Abbas aide says allegation meant to undermine peace bid
JERUSALEM, March 29 (Reuters) - Israeli Foreign Minister Avigdor Lieberman said on Monday Palestinian President Mahmoud Abbas urged Israel to topple Hamas in the Gaza war last year, then turned around and blamed Israel for war crimes.
Lieberman said that raised questions over Abbas's fitness as a leader with whom Israel could make peace.
"Over the past year, I witnessed (Abbas) at his best. In Operation Cast Lead, (he) called us personally, applied pressure and demanded that we topple Hamas and remove it from power," he told Israel's Maariv daily.
"A month after the operation ended, he filed a complaint against us with the International Court of Justice at The Hague for war crimes. Is that a partner?"
An aide to Abbas vehemently denied the allegation, accusing the right-leaning Israeli government of trying to deepen the deadlock over U.S.-sponsored efforts to revive negotiations.
"This is not true. It is a continuation of the (Israeli) campaign of defamation ... to create an atmosphere that would destroy any chance of salvaging the peace process," Abbas aide Nabil Abu Rdainah said.
Israel launched its three-week Gaza offensive on Dec. 27, 2008 with the stated aim of stopping rocket attacks by Hamas and other Palestinian factions. Such attacks have tapered off since, though there has been sporadic cross-border violence.
The war's Palestinian toll -- 1,400 dead, mostly non-combatants, while Israel lost 10 troops and three civilians -- drew fierce censure abroad and stalled negotiations between Abbas and then Israeli Prime Minister Ehud Olmert, a centrist.
Lieberman was not in government during the Gaza war. A spokesman declined to say on what the foreign minister had based his allegations. But a senior Israeli official serving Olmert at the time said Lieberman's account was "essentially accurate". Islamist Hamas, which has already accused its rival Abbas of cheering Israel on in the war, saw Lieberman's charge as vindication of its suspicions against the Palestinian president. "The grave statement reaffirms the fact Mahmoud Abbas is no longer fit to represent our people, who conspired against his people during a war," Hamas spokesman Sami Abu Zuhri said.
Hamas has been locked in a power struggle with Abbas's formerly dominant secular Fatah faction since winning a 2006 Palestinian election. It scorns Abbas for his recognition of the Jewish state and declared readiness to renounce armed struggle.
Abbas joined the condemnation of the Olmert government's Gaza offensive. But he outraged many Palestinians by initially vacillating over support for a U.N. war-crimes report in September that focused scrutiny on Israeli conduct.
In the Maariv interview, Lieberman was largely dismissive about prospects for progress with Abbas's government, whose mandate was cut down to the Israeli-occupied West Bank after Hamas seized the Gaza Strip and took full control in 2007.
Hopes of starting indirect talks between Israeli Prime Minister Benjamin Netanyahu and Abbas were dashed this month by the announcement of a new Jewish settlement project on occupied land where Palestinians seek a state.
The project, slated for an area of the West Bank that Israel annexed to Jerusalem, also drew U.S. questions about Netanyahu's seriousness about peacemaking. That dispute remains unresolved.
Additional reporting by Ali Sawafta in Ramallah and Nidal al-Mughrabi in Gaza; Editing by Douglas Hamilton and Dominic Evans
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