Masked gunmen claiming to be from Al Qaeda stormed a Gaza beach resort Tuesday and blew up a reception hall in an attack aimed at intimidating a strongman allied with Palestinian President Mahmoud Abbas, a witness said.

No one was hurt because the resort was empty, except for a few guards. But the assault threatened to spark a new wave of internal violence, casting a cloud over the next round of talks on forming a Palestinian unity government between Abbas' Fatah and the rival Hamas.

About 40 gunmen swarmed into the resort, which was a favorite of Israelis before Palestinian-Israeli violence erupted in 2000. A guard said the attackers hooked boxes of explosives and tanks of fuel to a battery and blew up the main hall, collapsing a huge glass ceiling and knocking down a wall. Other gunmen threw grenades at seaside cabins, destroying furniture and televisions.

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Resort manager Yousef Sari said the gunmen had a warning for Fatah strongman Mohammed Dahlan, an Abbas confidant. Dahlan has been rumored to own the resort but he says he does not.

"Tell Dahlan Al Qaeda has arrived in Gaza and his property and assets are targets," Sari quoted the attackers as saying.

Dahlan, one of the most feared and powerful figures in Gaza, served in senior security positions when Fatah was in power and cracked down hard on the Islamic militant group Hamas. He maintains control over armed forces in Gaza even though Fatah was ousted by Hamas in elections a year ago.

Dahlan is said to have played a behind-the-scenes role in months of fighting between armed forces of Fatah and Hamas that have killed at least 62 people.

Al Qaeda is not thought to have a presence in Gaza even though Abbas maintains it is operating there and the group has claimed responsibility for several attacks on Palestinian officials. Security officials say those claims are usually made by local militants or criminal gangs trying to divert attention.

Palestinian security officials said they were investigating the gunmen's claim that they belonged to the international terror group. Another possibility was a gang-style business dispute.

Fatah-Hamas violence has ebbed and flowed alongside negotiations over a unity government.

Over the weekend, Abbas met the top leader of Hamas, Khaled Mashaal, in Damascus. But they were unable to overcome basic disagreements. Another round of talks was scheduled for later Tuesday in Gaza.

The United States, Europe and Israel cut off funding to the Palestinian government after Hamas took power in March, listing Hamas as a terror group and demanding that the new government recognize Israel, renounce violence and accept previous peace accords.

Abbas, whose Fatah long ago accepted those points, has been trying to persuade Hamas to accept a formula to get Fatah back into government while allowing vital foreign aid to be resumed. Without the funds, the Palestinian government has been bankrupted, causing widespread hardship in the West Bank and Gaza.

Abbas has threatened to order new elections if a deal is not reached soon, but has set no firm deadline. Hamas threatens to boycott the voting, charging Abbas is trying to overthrow a democratically elected government. Abbas was elected separately two years ago.

Also on Tuesday, Gaza journalists went on strike to protest another act of violence -- the bombing of the Gaza City office of the Arabic satellite TV channel al-Arabiya late Monday. The channel has been in a dispute with Hamas over news coverage. The Hamas-led government and Abbas both condemned the attack.

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