TRIPOLI (AFP) - Nato bombs wrecked Libyan leader Moamer Gaddafis office in his immense Tripoli residence on Monday, while besieged rebel-held Misrata came under fresh attack by rockets which a doctor said had reduced civilian victims to little more than ashes. Heavy explosions shook the centre of Tripoli shortly after midnight as warplanes overflew the Libyan capital. A Libyan official accompanying journalists shortly afterwards at Gaddafis compound said 45 people were wounded, 15 seriously, in the bombing. He added that he did not know whether there were victims under the rubble. It was an attempt to assassinate Colonel Gaddafi , he affirmed. Seif Al-Islam, Gaddafis son, described the bombing as cowardly. This cowardly attack on Moamer Gaddafis office may frighten or terrorise children but we will not abandon the battle and we are not afraid, he said, claiming that Natos battle was lost in advance.Nato warplanes had already late Friday targeted the Bab Al-Aziziya district, where the presidential compound is located.At around 3:00 am (0100 GMT) smoke was still rising from part of the building that was hit, watched by dozens of people shouting slogans praising the Guide.