Fatah activists in the West Bank on Sunday called for lifting the parliamentary immunity from outgoing Palestinian Authority Interior Minister Said Siam of Hamas to pave the way for bringing him to trial on charges of committing crimes against the Palestinians. The call came amid reports that Siam and PA Foreign Minister Mahmoud Zahar of Hamas are spearheading efforts to foil the implementation of the "national unity" Mecca agreement. It also comes in the wake of renewed fighting between Fatah and Hamas gunmen in different locations in the Gaza Strip. This is the first time that Fatah representatives have called for putting a Hamas official on trial for allegedly committing crimes against the Palestinians. The appeal is likely to have a negative impact on efforts to form a Palestinian unity government. PA Prosecutor-General Ahmed al-Mughni revealed that Siam decided over the weekend to release a Palestinian who was arrested on suspicion of involvement in the assassination of Col. Jad Tayeh, a senior officer with the PA's General Intelligence Force in the Gaza Strip. Tayeh and four of his companions were killed when their car was ambushed north of the Gaza Strip several months ago. Fatah leaders then accused Hamas of being behind the assassination. Mughni expressed "regret" over Siam's decision to release the suspect even before he was questioned. He said Siam and the Hamas-led government have repeatedly ignored his orders to arrest Palestinians suspected of committing various crimes. The prosecutor-general also accused Siam of facilitating the escape to Egypt of a Palestinian who killed the driver of the Jordanian envoy to the PA last year. He complained that factional and tribal systems were hindering the work of the PA courts and prosecution. "We have issued more than 4,000 arrest warrants in the Gaza Strip, but none of them were carried out," he added. The Fatah youth movement (shabiba) in the West Bank said in a letter to the Palestinian Legislative Council that the time has come to lift Siam's immunity so that he could face charges of murder. "Siam is responsible for issuing orders to the death squads belonging to his ministry to perpetrate crimes against our people in the Gaza Strip," the letter said. "By refusing to dismantle the death squads, which are known as the Executive Force, Siam is violating the law. He is using this force to terrorize the public and extract concessions from his political rivals." Nayef Ishtaywi, spokesman for the shabiba, said Siam and Hamas were responsible for the collapse of the PA security establishment in the Gaza Strip. "They don't care about the law and consider themselves to be above the law," he said. "They don't even care about the sanctity of Palestinian blood." Siam drew sharp criticism from Fatah leaders over the weekend when he announced that the Hamas Executive Force would not be dismantled as agreed in Mecca. He said the force would continue to operate in the Gaza Strip until Abbas implements major reforms in the entire PA security establishment. Fatah and Hamas traded accusations over the fierce fighting that erupted on Saturday night between the two parties in Beit Hanun in the northern Gaza Strip. Muhammad Kafarneh, 27, a senior commander of Hamas' armed wing, Izaddin Kassam, was killed in the clashes with Fatah gunmen and PA security officers. Hamas said Kafarneh was killed in an ambush set by Fatah gunmen. Fatah, on the other hand, accused members of the Executive Force of raiding several houses and institutions and firing rockets at security headquarters. On Sunday evening, Fatah gunmen kidnapped nine Hamas militiamen in Beit Hanun, further escalating tension between the two sides. Sources close to Hamas confirmed that a dispute has erupted among the movement's leaders over the Mecca agreement. They said Siam and Zahar, who are expected to lose their jobs in the new Hamas-led coalition, were strongly opposed to the unity government with Fatah. Evidence of the deepening crisis in Hamas emerged Sunday when a splinter group called The Sons of [former Hamas leader and founder] Ahmed Yassin warned Siam and Zahar against trying to sabotage the Mecca deal. "Sadly, some Hamas leaders who are sticking to their seats don't care about anything but their private interests," the group said in a leaflet. "We warn these two ministers against spreading chaos and lawlessness and trying to undermine the honorable leaders in Hamas." A meeting that was scheduled to be held between Fatah and Hamas representatives in the Egyptian embassy in Gaza City was called off due to increased tensions between the two sides, a top Egyptian diplomat told The Jerusalem Post. The diplomat expressed concern that some elements in Hamas and Fatah were trying to renew the fighting to thwart the implementation of the Mecca agreement. "The situation on the ground is very dangerous," he said. "There is a feeling that an all-out confrontation could erupt at any time in the Gaza Strip."