Rebels fighting to overthrow Muammar Gaddafi have rejected an offer from the Libyan leader to negotiate his exit even as they battled to hang on to early gains in the insurrection. The frontline in east Libya was static on Tuesday, with forces loyal to Col. Gaddafi and rebels manning defences in a stretch of barren coastline near oil terminals between the towns of Ras Lanuf and Bin Jawad, about 550 km east of Tripoli.