Pro-Gaddafi forces have launched a surprise attack on Libyan rebels in Ajdabiya, shelling the town and deploying soldiers on the streets.

The rebels said they had managed to repulse the attack after several hours of fighting.

Doctors said eight rebels were killed in the violence.

In the western city of Misrata, Nato forces have intensified their air strikes and destroyed 15 tanks after an upsurge of violence.

Rebel leaders have been critical of Nato's attempts to enforce a UN-mandated no-fly zone, particularly since an air strike hit a rebel convoy earlier this week.

But rebel commanders now say they are heartened by the intensification of strikes on pro-Gaddafi forces on Friday and Saturday.