A group calling itself al-Qaida in Palestine threatened on Sunday to assassinate Palestinian Authority Chairman Mahmoud Abbas and other leaders of his Fatah party. The group also claimed responsibility for Saturday's attempt on the life of Tarek Abu Rajab, commander of the PA's General Intelligence Service, who was seriously wounded when a bomb exploded inside an elevator in his headquarters in Gaza City. One of his bodyguards was killed and 10 others were wounded in the blast. Meanwhile, PA security officials revealed that Hamas was purchasing more weapons ahead of a possible confrontation with Fatah in the West Bank. "They are buying weapons from various sources," said one official. "They are even buying large amounts of weapons from Fatah dealers and this is very worrying." In a leaflet distributed in the Gaza Strip, al-Qaida in Palestine said: "We declare our full responsibility for this operation. Your warrior brothers managed to place a bomb in the special lift used by the apostate Tarek Abu Rajab, but were hasty in detonating the device which should have been triggered once the lift door was closed." The group also threatened to kill other "apostate" PA officials, including Abbas, former security chief Muhammad Dahlan and top Fatah leader Abu Ali Shaheen. This is the first time that the group issued a direct threat against Abbas. Two weeks ago, another al-Qaida-linked group issued a leaflet in which it threatened to "slaughter" Dahlan and some Fatah leaders under the pretext that they were conspiring with the US and Israel to bring down the Hamas government. The latest threat came as PA security forces announced that they had thwarted an attempt to assassinate Rashid Abu Shabak, the overall commander of the PA security services and a Fatah leader. PA security sources said a large bomb was discovered on Sunday morning next to Abu Shabak's home in Gaza City. They said the 70-kilogram device, which was found alongside the road used by Abu Shabak's convoy, was safely detonated by bomb experts. Following the incident, hundreds of Fatah gunmen took to the streets, firing into the air and shouting slogans in support of Abu Shabak and Abbas. The gunmen also expressed their readiness to volunteer for the PA security forces to protect their leaders. Fatah's armed wing, the Aksa Martyrs Brigades, issued a statement in which they claimed that Israel was behind the growing tensions between the party and Hamas. "There is no presence for al-Qaida in Palestine," the group said. "These are only Israeli claims. Israel and its agents are behind the recent confrontations in the Gaza Strip." In a separate development, scores of Palestinians marched in Ramallah to protest the torching of three cars belonging to Al Jazeera on Saturday night. The attack was apparently carried out by Fatah activists who were enraged by the network's failure to cover a Fatah demonstration in the city earlier in the day. Fatah leaders have also expressed their dismay with the Qatar-based station for airing interviews with Hamas leaders and for carrying live coverage of Prime Minister Islmail Haniyeh's Friday sermons in mosques in the Gaza Strip. In Gaza City, dozens of Palestinian journalists staged a sit-in strike to protest the attack on Al Jazeera and other assaults on their colleagues over the past few weeks. On Saturday, several Palestinian journalists who arrived to cover the explosion at the headquarters of the General Intelligence Service in Gaza City were beaten by security officers. Fatah and Hamas leaders who participated in the protest condemned the targeting of journalists and urged the PA security forces to take immediate action against the perpetrators.