Col Muammar Gaddafi's Tripoli compound was targeted by coalition air strikes on Wednesday night as a senior British commander said the Libyan air force had been destroyed.

Five loud blasts were reported at Gaddafi's Bab al-Aziziya compound, where he had made an address on Tuesday night and which had been first attacked on Sunday night.

There were eight further large explosions heard in the east of the capital and at a military base in Tajura, 20 miles to the east of the city.

State television reported "a large number of civilians" had been killed.

In the eastern city of Misurata, rebels have been besieged by Gaddafi's forces for weeks, but said allied air strikes had offered much-needed respite.

RAF Air Vice-Marshal Greg Bagwell disclosed that allied forces had all but wiped out the Libyan air force and were attacking ground troops wherever they threatened the civilian population. "We are now applying sustained and unrelenting pressure on the Libyan armed forces," he said, during a visit to the RAF base at Gioia del Colle in southern Italy. "Effectively, their air force no longer exists as a fighting force and their integrated air defence system and command and control networks are severely degraded to the point that we can operate with near impunity across Libya."

There were further reports of renewed fighting in Ajdabiya in the east and Zintan in the west. US Rear Adm Gerard Hueber, chief of staff of the Joint Task Force, confirmed that Gaddafi's forces were attacking Misurata and Ajdabiya with tanks, artillery and rocket launchers. On Tuesday night government tanks reportedly bombarded Misurata's hospital.

"Our primary focus is to interdict those forces before they enter the city, cut their lines of communication and cut their command and control," he, said, speaking by telephone aboard the US command ship, the USS Mount Whitney, in the Mediterranean.

Mohamed, a spokesman for the rebels in Misurata, said: "We almost lost all hope, but the strikes came at a good time with good intensity and frequency."

Adm Samuel Locklear, the head of the US forces in Libya, said coalition aircraft planned to target the Libyan army's 32nd Brigade, a "premier force for Col Gaddafi", in the "coming hours and days". The unit, led by Gaddafi's youngest son, Khamis, is estimated to have as many as 10,000 troops.

Although the coalition has insisted there will be no boots on the ground, American ships in the Mediterranean - on standby to carry out humanitarian operations - are also crammed with Humvees, armoured trucks and weaponry and are capable of delivering hundreds of Marines to beach landings.

A US military official said the wreckage of an F-15 fighter jet that went down in eastern Libya on Tuesday had been bombed "to prevent materials from getting into the wrong hands".