( CNN ) -- Forces loyal to embattled Libyan strongman Moammar Gadhafi launched a new attack on the rebel-held city of Misrata on Wednesday , with anti-government forces reporting intense shelling from three sides of the city . Thousands of government troops attacked around 6 a.m. ( 11 p.m. Tuesday ET ) , with 13 rebels reported dead by evening . Mohamed Mokhtar , a rebel fighter wounded in Wednesday 's fighting , accused government troops of infiltrating rebel lines in cars bearing rebel flags . Dr. Khaled Abu Falgha , a spokesman for Misrata 's Hekma hospital , said it was the bloodiest day in a week in the besieged city . More than 1,000 people are believed to have been killed since the fighting began there in February , including 686 registered residents of the city , he said . Rebel fighters returning from the front lines reported that their defenses were holding up under the onslaught , however . The assault followed a day of intense bombardment of Libya 's capital by the NATO alliance , which intervened in the conflict in March under a U.N. mandate to protect civilians as Gadhafi tried to crush the revolt against him . Libya 's government said 60 missiles struck the capital city , killing at least 31 people , including a number of civilians , and wounding dozens more . NATO Secretary General Anders Fogh Rasmussen reiterated Wednesday that the alliance is doing all it can to avoid civilian casualties . But he told reporters from allied headquarters in Brussels , Belgium , that NATO could continue the airstrikes `` for as long as it takes to bring this crisis to an early conclusion . '' Rasmussen said NATO bombing has saved lives in Libya , and that the alliance has the resources to extend its military mission for another 90 days past the end of June . It is time to start planning for what to do after Gadhafi 's departure `` because Gadhafi 's reign of terror is coming to an end , '' he said . Pressed by reporters on why airstrikes would be able to dislodge Gadhafi when `` the history of the last 30 years '' shows that air attacks alone do not win wars , Rasmussen offered no clear answer , saying only , `` We have no intentions to put troops on the ground . '' For his part , even as NATO airstrikes bombarded his Tripoli compound , Gadhafi vowed Tuesday that `` we will not surrender . '' `` I am now speaking as planes and bombs fall around me , '' Gadhafi said in a live audio broadcast on state television . `` But my soul is in God 's hand . We will not think about death or life . We will think about the call of duty . '' The Gadhafi compound was under `` intensive continuous bombardment , '' according to state TV , which reported buildings and infrastructure were destroyed . But government spokesman Musa Ibrahim said the allied campaign `` is failing miserably . '' `` No one has the right to shape Libya 's future except for Libyans , '' he said . Ibrahim said Tuesday 's morning blasts hit the popular guard compound and the revolution compound , which are military barracks near Gadhafi 's Bab al-Aziziya compound . The spokesman said attacks Tuesday and Wednesday hit state television buildings , killing two people and wounding 16 . NATO disputed the account . `` We did not target or hit the Libyan broadcast facilities . What we did target was the military intelligence headquarters in downtown Tripoli , '' the alliance said . `` The story coming from Libyan officials that we targeted and hit the state broadcaster 's building is bogus . '' CNN 's Amir Ahmed , Richard Allen Greene , Raja Razek , Dan Rivers and Jonathan Wald contributed to this report .
NATO : A fresh attack on rebel - held territory has killed at least 13 , they say . NATO says it is doing all it can to avoid killing civilians . NATO chief also says Gadhafi 's ` ` reign of terror '' is ending soon . Gadhafi vows not to surrender amid heavy fighting .