Rebel leaders in Misrata say progress towards the capital Tripoli is being hampered by a lack of ammunition and inadequate support from Nato.
On Wednesday, officials in the rebel-held city said 17 of their fighters were killed and more than 60 wounded.
Rebel forces and soldiers loyal to Col Muammar Gaddafi have been locked in a stalemate to the west of Misrata for more than six weeks.
A rebel spokesman said Nato air cover was patchy, with deadly consequences.
"When the aircraft is flying in the sky... it means Gaddafi's forces cannot use rocket launchers on the ground, they are afraid [of] aircraft... observing them and... striking them," Fatti Bashada told the BBC's Gabriel Gatehouse, near Misrata.
Mr Bashada said that despite repeated requests to keep patrolling the skies, Nato aircraft have, in recent days, disappeared half-way through a battle.
"When there's no flight, it means they are free to use any weapons against us," he said, adding that rockets fired by Col Gaddafi's fighters were killing an increasing number of rebels. |