Libyan militias, operating alongside the Defence Ministry, have deployed their forces around a former stronghold of ousted dictator Muammar Gaddafi, officials said on Wednesday, stoking fears of impending fighting.The forces are surrounding parts of the town of Bani Walid, a week after the death of former Misrata rebel fighter Omran Shaban, which has raised tension between the rival towns that backed opposing sides in last year’s war.Shaban, who helped capture Gaddafi last year, was kidnapped by armed men in July close to Bani Walid while on his way back to Misrata after he had been on government business in western Libya to calm clashes there.His relatives said he had been shot and tortured while in their hands. The ruling national congress ordered the Defence and Interior Ministries to find those who abducted him. Leaders in Bani Walid have been given until Friday to hand them over and elders had travelled to the town for negotiations.The renewed tension comes at a difficult time for Libyan leaders, trying to impose order on armed groups after the killing of the U.S. ambassador in a fatal assault on the U.S. consulate in Benghazi on September 11. "The congress has given the Defence and Interior Ministries the order to follow up on what happened,” Ramadan Ali Zarmoh, of the Misrata military council, told Reuters."The forces are only surrounding it for now ... What happens next depends on the decision from the congress. Maybe a solution can still be negotiated.”