Libyan leader Moamar Gaddafi's office in his immense Tripoli residence was destroyed in an air strike early on Monday, an AFP journalist reported.

Firefighters were still working to extinguish flames in a part of the wrecked building when journalists were brought on a government-organised trip to the scene, a few hours after three loud explosions shook central Tripoli.

A Libyan official accompanying journalists at the scene 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.

A meeting room facing Mr Gaddafi's office was badly damaged by the blast.

Earlier, state-run television stations went off air after heavy explosions shook the Libyan capital.

The blasts, reported by AFP to be the strongest to have hit the city so far, shook the hotel in which foreign correspondents are staying not far from the city centre.

Libyan Television, Jamahiriya and Shababiya all stopped broadcasting but returned to air within 30 minutes.

NATO has been carrying out intensive air raids on Tripoli since Friday.

The western Libyan city of Misrata came under heavy bombardment on Sunday one day after government forces said they were pulling back from their siege of the Mediterranean port.

Salvos of Grad rockets and automatic weapons fire targeted Misrata in an apparent contradiction of the regime's claims that its troops have halted operations in the port city to allow tribes to solve the conflict.

Captured government troops said they had been ordered to retreat from the coastal city after a siege of nearly two months, and rebels fighting to overthrow Mr Gaddafi had claimed victory on Saturday (local time).

"The situation is very dangerous," rebel spokesman Abdelsalam said by telephone from Misrata.

"Gaddafi's brigades started random bombardment in the early hours of this morning. The bombardment is still going on. They targeted the city centre, mainly Tripoli Street, and three residential areas."

Another rebel spokesman, the Transitional National Council's Colonel Omar Bani, said Mr Gaddafi was playing "dirty games" and trying to divide tribes in the besieged western city.

"Gaddafi is playing a really dirty game," he said.

"It is a trick, they didn't go ... They have stayed a bit out of Tripoli Street but they are preparing themselves to attack again."

Hundreds have been killed in the fighting for Misrata, the only major rebel-held city in western Libya.

In the rebels' eastern stronghold, Benghazi, a rebel military spokesman said he too was sceptical about the pull-out from Misrata by Mr Gaddafi's forces.

"I don't think this is a real withdrawal," spokesman Ahmed Bani said.

He suggested government loyalists may be trying to stoke tensions between Misrata and neighbouring towns, and that Mr Gaddafi's troops might return to Misrata later under the guise of intervening to protect local tribes from the rebels.

"Gaddafi wants to make it seem like this isn't a problem between the people and him, but a problem between the people and the tribes. This is a dream," he said.

Libyan deputy foreign minister Khaled Kaim said on Friday the army would "leave it to the tribes and the people around Misrata to deal with the situation whether by using force or using negotiations".

Britain and France have been leading air strikes against Mr Gaddafi's forces in an operation mandated by the UN Security Council on March 17 to protect civilians in Libya.

The United States has also deployed Predator drones, using the unmanned plane for the first time on Saturday to attack the site of a multiple rocket launcher near Misrata.

Rebels have so far, however, been unable to advance from eastern Libya and have instead fought back-and-forth battles with Mr Gaddafi's troops on the coastal highway between the towns of Ajdabiya and Brega.

- AFP/Reuters