Gunmen linked to Palestinian President Mahmoud Abbas' Fatah movement threatened Tuesday to assassinate leaders of the rival Hamas group — heightening tensions from three days of fighting that has killed 10 Palestinians.

The violence, the worst since Hamas took office in March, heightened fears of a full-scale civil war. The fighting came after efforts broke down last week to bring Fatah into the government.

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Abbas, who had hoped a broader and more moderate coalition would end an international boycott of the Hamas government, is running out of options to end the crisis created by the aid cutoff.

Abbas had considered calling early elections, but polls indicate Fatah would tie with Hamas. Also, a poll published Tuesday showed voters consider Abbas less trustworthy than Prime Minister Ismail Haniyeh of Hamas.

The U.S. and moderate Arab states were making a new push to revive Israeli-Palestinian peace talks. U.S. Secretary of State Condoleezza Rice and the foreign minister of Bahrain, Shaikh Khalid Bin Ahmed Al-Khalifa, were to hold separate talks with Abbas on Wednesday.

The threat to kill Hamas leaders came in a statement by the Al Aqsa Martyrs' Brigades, a violent Fatah offshoot. A caller reading from the statement told The Associated Press that Al Aqsa would try to assassinate Interior Minister Said Siyam, Hamas militia chief Youssef Zahar and the group's supreme leader in exile, Khaled Mashaal.

"We are going to implement the rule of the people and the revolution by executing the heads of this seditious group," the caller said. Al-Aqsa confirmed the authenticity of the statement when contacted by the AP.

The latest round of fighting began Sunday, when Hamas militiamen used beatings and gunfire to put down protests by civil servants and members of the security forces who demanded payment of salaries.

The confrontations triggered armed clashes over the weekend between the 3,500-strong Hamas militia and the Fatah-dominated security forces. In all, 10 people were killed and more than 100 wounded.

The violence also spread to the West Bank, where Fatah militants torched the Cabinet building in Ramallah and trashed Hamas offices.

On Monday, Fatah militants shot at bodyguards of Deputy Prime Minister Nasser Shaer of Hamas as they rode in a government car, injuring two of them. Shaer was not present during the attack. Hospital officials said a Fatah militant also was injured.

The Palestinian Authority's 165,000 government employees have largely gone unpaid for seven months because of the international aid freeze. Many of the civil servants have been on strike for the past month, though compliance in schools has been spotty, particularly in Gaza.

On Tuesday, Fatah gunmen closed several schools in central Gaza by force. The gunmen also blocked a major intersection, shouting "Down, down with Hamas!" burning tires and garbage and shooting in the air.

Ghazi Hamad, a spokesman for the Hamas government, called for a new effort to establish a national unity government with Fatah, but also condemned the civil servants' strike.

"I know there is suffering and there is a big problem," Hamad told Israel Radio, speaking in Hebrew. "When there is a strike you don't go to work but you don't cause problems and riots all the time. This is not acceptable to us."

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