Libya's interim rulers said they had captured one of Muammar Gaddafi's last strongholds deep in the Sahara desert, finding a secret stock of chemical weapons, and had largely taken control of another. Poorly-organised fighters with the National Transitional Council (NTC) were still struggling to make inroads at two other pro-Gaddafi redoubts, and commanders were trying to stop chaotic weapons handling that has already killed several fighters in “friendly fire” incidents. Reuters saw one fighter blow his own head off and kill a comrade while handling a rocket propelled grenade. If the NTC is unable to swiftly assert its control over the country and its own forces, it could embarrass Western leaders, especially France's Nicolas Sarkozy and Britain's David Cameron, who took a gamble by backing the anti-Gaddafi leadership. The NATO alliance has extended a six-month bombing campaign for another 90 days to continue air strikes to support the NTC. The interim government controls the capital and most of the oil exporting country's territory after its fighters, with support from NATO warplanes, swept Gaddafi from power a month ago. The deposed ruler himself is still at large and could be in one of the outposts being fought over. The NTC's military spokesmen said its forces had seized the outpost of Jufra about 700 km (435 miles) southeast of Tripoli, and most of Sabha, a larger town further south which is the traditional base of Gaddafi's tribe. “The whole of the Jufra area – we have been told it has been liberated,” spokesman Fathi Bashaagha told reporters in the city of Misrata late on Wednesday. “There was a depot of chemical weapons and now it is under the control of our fighters.”His comments could not be confirmed independently. Under Gaddafi, Libya was supposed to have destroyed its stockpile of chemical weapons and abandon its nuclear programme in early 2004 as part of a rapprochement with the West. The Organisation for the Prohibition of Chemical Weapons says Libya kept 9.5 tonnes of mustard gas at a secret desert location. Gaddafi loyalists have been holding out in Jufra and Sabha along with the bigger strongholds of Bani Walid, southeast of Tripoli, and Gaddafi's hometown of Sirte, since the fall of the capital in August. “We control most of Sabha apart from the al-Manshiya district. This is still resisting, but it will fall,” said another NTC military spokesman, Ahmed Bani. CNN, citing a correspondent in Sabha, reported that NTC fighters had occupied its centre on Wednesday after taking the airport and a fort the day before. However, chaos prevailed among fighters besieging Gaddafi's other two remaining major strongholds. Several attempts by NTC fighters to take Bani Walid and Sirte in the past week have ended in disarray and panicked retreat. North of Bani Walid on Thursday morning, NTC military forces were bringing forward tanks and Grad rocket launchers in preparation for a renewed attempt to take the town. It was not clear though when that attack would begin. The offensive there has been frustrated by stiff resistance from well-drilled loyalist fighters, and also by a lack of organisation among the NTC forces. They operate in disparate units based on their home town, with little overall command.