Misrata, closer to Tripoli, has also come under heavy attack and blasts have been reported in the capital.

Meanwhile London has been hosting a key summit on the future of Libya.

Anti-Gaddafi forces had made rapid progress westwards from their stronghold in Benghazi in recent days - greatly aided by international air strikes - seizing a number of coastal communities and important oil installations, including Ras Lanuf, Brega, Uqayla and Bin Jawad.

The rebels had reached Nawfaliya, 120km (75 miles) from Col Gaddafi's birthplace of Sirte, but pulled back to Bin Jawad, some 30km further east.

There was intense fighting over Bin Jawad, forcing the rebels to abandon the town and flee back towards Ras Lanuf in a convoy of hundreds of vehicles.

Most fighters have now also pulled out of Ras Lanuf, says our correspondent, in an indication of their lack of arms, organisation and their inadequate supply lines.