BENGHAZI, Libya (Reuters) - Libyan rebels begged for more Nato air strikes on Thursday, saying they faced a massacre from government artillery barrages on the besieged city of Misrata, but Western allies squabbled over how to respond. Rebels said a hail of rockets fired by besieging forces into a residential district of Misrata, Libya's third largest city, had killed 23 civilians, mostly women and children. Aid organisations warn of a humanitarian disaster in Misrata, the lone major rebel bastion in western Libya, where hundreds of civilians are said to have died in a six-week siege. NATO warplanes later launched strikes on Tripoli. Reuters journalists in the capital heard four blasts and anti-aircraft fire, and saw plumes of smoke to the southeast. Libyan state television showed Muammar Gaddafi driving around the capital, saying it was during the attacks. Wearing a green canvas safari hat and dark glasses and looking ebullient, he stood out of the top of an SUV pumping his fists and waving as passers by and other drivers cheered. State television said there were civilian casualties from air strikes on the capital, which could not be confirmed. "A massacre...will take place here if NATO does not intervene strongly," a rebel spokesman in Misrata told Reuters by phone. Reports of casualties are hard to verify in the isolated city. Al Jazeera television showed hundreds of Misrata residents demonstrating after the dawn attack. "The blood of martyrs will not be in vain," they chanted, waving the rebel flag. The International Organisation for Migration said a rescue ship had left Benghazi, in rebel-held east Libya, to begin evacuating 6,000 stranded migrants from Misrata. Many were dehydrated and weak and in "desperately worrying condition," it said. Migrants from Egypt, Niger, Bangladesh, Ghana, Sudan and Nigeria have been stranded in Misrata, living in the open for weeks with limited food and no clean water.