BENGHAZI (AFP) - A deadly clash broke out in Libya's rebel capital of Benghazi in the wake of the murder of their military chief, as the Gaddafi regime said Sunday it was in contact with rebel leadership members. Four rebels were killed in the clash with a pro-Gaddafi group in Benghazi overnight, a rebel spokesman said. "It was a long battle and it took many hours because they were heavily armed," Mahmud Shamman told AFP. "In the end we arrested 31 of them. We lost four people." He said the group, which suffered "about 20 casualties," was rounded up for its role in organising a prison break in Benghazi earlier in the week. Rebel forces had surrounded the camp of the group linked to Libyan leader Moamer Gaddafi after they refused to obey an order from the rebels' National Transitional Council (NTC) for all militias to disband and lay down their arms. The clash follows last week's assassination of rebel military chief General Abdel Fatah Yunis, whose death remains cloaked in mystery. The general was a right-hand man to Gaddafi before his defection to the rebel ranks. Fareed Juwayli, head of security in Benghazi, said a rebel militia had uncovered the group linked to Gaddafi's regime holed up in a licence plate factory. Among them were several prisoners who had escaped in the prison break, the security chief said. The clash broke out after the suspects refused to surrender. The group "had plans to plant car bombs in Benghazi," according to Mustafa al-Sagazly, deputy chief of the militia, the February 17 brigade. "We found a large number of explosives typically found in car bombs." While the rebels have been trying to quash rumours about the mysterious death of their army chief, the Gaddafi regime said on Sunday that it was in contact with members of the NTC. "There are contacts with Mahmud Jibril (number two in the NTC), and (Ali) Essawy (in charge of external relations), (religious leader Ali) Sallabi and others," deputy foreign minister Khaled Kaaim told a Tripoli news conference. Gaddafi on Saturday night renewed his pledge "never to abandon" the battle, in an audio tape broadcast on state television despite NATO air strikes earlier the same day on the broadcaster's headquarters in Tripoli. Libya's enemies would be "defeated in the face of the resistance and courage of the Libyan people," he said in a speech following the strikes which Tripoli said killed three journalists. The rebels, who have frequently denied having had any direct negotiations with Tripoli, sought to stamp out rumours by giving details on Yunis's killing and bringing all militias under the control of the NTC interior ministry. Meanwhile, the Benghazi villa of the murdered general was surrounded by checkpoints early on Sunday and no traffic allowed on the coastal city's main highway.