Explosions rattled the Libyan capital early yesterday as Russia prepared to send an envoy on a shuttle mission to try to broker a negotiated settlement between its Cold War ally and the rebels.

Four explosions were heard at 11.35 p.m. (2135 GMT) on Thursday from the centre of Tripoli, followed by others about 15 minutes later.

Then at 1.45 a.m. (2345 GMT), four powerful blasts shook the district where Col Gaddafi’s residence is located not far from the city centre.

An army barracks in the same sector had been the target of several raids last week.

Earlier this week, government spokesman Mussa Ibrahim said Nato air raids on Libya had killed 718 civilians and wounded 4,067 since they were unleashed on March 19 and up to May 26.

In Washington, US military chief Admiral Mike Mullen pointed to “some signs, certainly in the last few days, that Col Gaddafi is becoming more and more isolated”.

He noted the defection of oil minister Shukri Ghanem, who had been a key figure in the regime, along with a group of “young generals” who had also parted with Col Gaddafi.

Mr Mullen welcomed Nato’s extension of its UN-mandated mission to protect civilians through military action until late September.

Russian President Dmitry Medvedev said Moscow will be sending an envoy to Tripoli and the rebels’ capital of Benghazi to mediate, the Italian news agency Ansa reported, quoting diplomats.

Mr Medvedev stressed the importance of a negotiated settlement at talks with Italian Prime Minister Silvio Berlusconi in Rome.

“We would like as much as possible for the problem to be resolved through negotiations and not by military means,” Mr Medvedev told reporters.