Crude output slips for first time since port deal; fresh clashes in Tripoli and Benghazi. Brega oil port seen open in few days. A twin suicide bombing at a Libyan army base in Benghazi killed at least four solders in an escalation of clashes between Islamist militants and regular forces battling to oust them from the eastern city. A first attacker blew himself up at the entrance to Benghazi's special forces headquarters, allowing a second suicide bomber to detonate his explosives at the base and kill at least four troops, a security source said. Suicide bombings are rare in Libya, where a fragile government is struggling to impose order. Tripoli and Benghazi are now caught up in some of the fiercest fighting between rival armed groups since the fall of Muammar Gaddafi in 2011.