The Libyan government dismissed rebel denials that the two sides have been holding talks and hit out at NATO\'s air war late on Friday as Muammar Gaddafi defiantly vowed the alliance was doomed to defeat. Addressing a news conference in Tripoli just hours after loud explosions again rocked the Libyan capital, Prime Minister Baghdadi al-Mahmudi accused NATO of committing \"war crimes and crimes against humanity\" by \"directly targeting civilian sites\" with air raids over the past three days. State television aired Gaddafi\'s comments in what it said was a live telephone call from the Libyan leader, who has gone underground since the Western-led air war was launched in March, as thousands of his supporters gathered in Tripoli\'s Green Square for their biggest rally in weeks. Baghdadi said that the governments of the countries where regime envoys had approached rebel representatives were fully aware that multiple contacts were under way as detailed by Russian envoy Mikhail Margelov. \"Ask the Egyptians, French, Norwegians and Tunisians for information. They will tell you the truth,\" Baghdadi said. \"We are sure of our meetings and everything has been recorded.\" Speaking earlier on Friday a day after visiting Tripoli, Margelov said that the Libyan government had forged multiple contacts with the Libyan opposition in foreign capitals including Berlin, Paris and Oslo. The comments from the Russian envoy, who visited the rebels\' eastern stronghold of Benghazi last week, drew a swift denial from their National Transitional Council. \"I can assure you there is and there was no negotiation between the NTC and the regime,\" the council\'s head of international affairs, Mahmud Jibril, said. An NTC official in Benghazi was even blunter. \"Gaddafi must go. Anyone from the rebel side who negotiates his staying in power would immediately have an NTC arrest warrant issued against him,\" the official told AFP, speaking on condition of anonymity. France said it had no knowledge of any negotiations. \"If there have been direct contacts, we\'re not involved and we didn\'t set them up,\" foreign ministry spokesman Bernard Valero said. In his speech, broadcast by loudspeaker to the flag-waving supporters in Green Square, Gaddafi said the government would not accept any reforms imposed from abroad. \"We are determined to change nothing in our country other than by our own free will... We are resisting, we are fighting,\" he said. \"NATO is bound to be defeated.\" The Libyan prime minister denied allegations being investigated by prosecutors of the International Criminal Court that loyalist forces had been carrying out mass rapes as matter of deliberate policy. \"Neither our morals nor our religion permit it,\" Mahmudi said. He called for \"an urgent meeting\" of the United Nations to examine \"crimes committed by NATO against Libyan civilians,\" charging that the alliance had hit targets including a university and a hotel in Tripoli on Friday. In the United States, the New York Times reported that President Barack Obama overruled two senior government lawyers in deciding that he did not need Congressional approval to extend US participation in the Libya campaign, adding grist to a building political row over the conflict. In reaching his conclusion Obama rejected the opinions of Jeh Johnson, the Pentagon general counsel, and Caroline Krass, the acting head of the Justice Department’s Office of Legal Counsel, The Times reported, citing unnamed officials familiar with the deliberations. Johnson and Krass both told the White House they believed that US military activity in the NATO-led air war over Libya amounted to \"hostilities\" requiring Congressional authorisation. Republican House Speaker John Boehner sent a scathing letter to the president earlier this month warning that US operations would be illegal come Sunday because they lacked such approval. In fighting on the ground on Friday, the rebel-held third city of Misrata came under deadly rocket attack but rebel fighters seized a key stretch of road towards the Tunisian border. Gaddafi forces fired a volley of Grad rockets into the Mediterranean port city -- the rebels\' most significant stronghold in western Libya -- killing 10 people and wounding 40, all of them civilians, rebel spokesman Ahmed Hassan told AFP. In the rebels\' other western enclave, the Nafusa Mountains southwest of the capital, their fighters took complete control of the road between the towns of Zintan and Yafran, an AFP correspondent reported adding that the highway was dotted with destroyed tanks and abandoned government vehicles.