Lebanese troops on Saturday set up checkpoints and searched cars going in and out of a Palestinian refugee camp near the northern city of Tripoli where a militant group blamed for last month's deadly bus bombings is based, camp residents and military officials said. Soldiers searched all vehicles entering or leaving the Nahr al-Bared camp and banned media and Lebanese citizens from going inside. Schools in the camp were closed and Palestinian students who study outside Nahr al-Bared were prevented from leaving, said camp residents reached on the phone. The residents declined to give their names because of the sensitivity of the situation. They said many shops inside the camp, which is home to about 30,000 Palestinians, had closed and that traffic was light. A senior Lebanese military official, speaking on condition of anonymity because he was not authorized to talk to the media, said there were security "measures around the camp" because detained members of a militant group based in the camp had confessed to the bombings. "The case is continuing since we have people who confessed to have carried an attack," the official said without providing details how long the measures would last. Earlier this week, Lebanese Interior Minister Hassan Sabei announced the arrests of four Syrian members of the little-known Fatah Islam group - an alleged offshoot of the Damascus-based Palestinian Fatah Uprising. The arrested, Sabei said, had confessed to being behind the Feb. 13 bombings of two buses on a mountain road northeast of Beirut that killed three and wounded 20 people. Sabei also implicated Syrian intelligence agency in the bombings and claimed that Fatah Islam's alleged split from the Damascus-based group was a cover and that the two were essentially the same. Fatah Islam reportedly split from Fatah Uprising, itself a 1980s splinter of the late Palestinian leader Yasser Arafat's mainstream Fatah party. Fatah Islam rejected Sabei's bombings charges, as did Fatah Uprising and the Syrian government. In Damascus, Fatah Uprising said it has not links with Fatah Islam while Syrian Interior Minister Bassam Abdul-Majid accused Fatah Islam of being affiliated with the al-Qaida terror group and of allegedly planning terrorist acts in Syria. Lebanese military involved in the security boost on Saturday at Nahr al-Bared was not expected to enter the camp - all 12 Palestinian camps in Lebanon are off limits to the Lebanese military. Meanwhile, dozens of camp residents held a sit-in to protest the military measure. But local television, including the Lebanese Broadcasting Corp., and Voice of Lebanon radio station said the sit-in was a protest against the presence of the militant group and that camp residents had asked the group to leave the camp. Also Saturday, visiting Palestinian Authority official and Chairman Mahmoud Abbas's senior security adviser, Jibril Rajoub, denounced the Fatah Islam group, saying it "does not serve the Palestinian cause." "The resistance should be in Palestine only and nowhere else," Rajoub, who is in Beirut for an academic conference, told reporters.