Libya's deposed leader Muammar Gaddafi has issued a defiant audio message warning his opponents that Nato protection cannot last indefinitely.The message, the third since he was ousted last month, was broadcast on the Syria-based Arrai TV network.It comes as representatives from the US and its allies prepare to meet to discuss a post-Gaddafi future.Col Gaddafi has been in hiding since opposition forces captured the capital Tripoli in late August."The political system in Libya is a system based on the power of the people," he said in the message. "It is impossible that this system be removed."Do not rejoice and don't believe that one regime has been overthrown and another imposed with the help of air and maritime strikes."The bombs of Nato planes will not last," he added. It is not known when or where the message was recorded.Mercenary claimTuesday's meeting, to be held on the sidelines of the UN General Assembly, comes after the first talks between US President Barack Obama and Mustafa Abdel Jalil, the head of Libya's National Transitional Council (NTC).French Foreign Minister Alain Juppe, speaking on Monday, said the talks would "confirm the start of a new phase which began with the Paris summit and the beginning of an increased role in the United Nations".According to the AFP news agency, Mr Juppe said one purpose of the talks would be to create a Friends of Libya group to replace the Contact Group which was created on 29 March in London.The group gathers some 30 countries and several international organisations, including the UN, Nato and the Arab League.Fighting continues in Libya for control of Bani Walid and Col Gaddafi's birthplace, Sirte, where pro-Gaddafi fighters are mounting fierce resistance.Anti-Gaddafi forces launched an offensive on Bani Walid, 140km (90 miles) south-east of Tripoli, on Thursday and again on Friday, but were forced to retreat under heavy fire both times. Heavy clashes have continued since then.Claims by Col Gaddafi's spokesman that loyalists had captured 17 foreign mercenaries during recent fighting have been denied by western powers and the NTC.Moussa Ibrahim said on Monday that the mercenaries were "technical experts and consultative officers", adding that most were French, one was from an unidentified Asian country, two were English and one was from Qatar.Mr Juppe said there were "no French mercenaries in Libya", while the British foreign office said it had no information about whether the report was true. Nato says it has no troops on the ground in Libya.