At least 22 people have been killed and up to 60 more injured following a renewed barrage of shelling by Libyan troops around the city of Misrata.

The city is the main rebel stronghold in western Libya, and has the country’s largest port.

Meanwhile, Turkey said it has offered Muammar Gaddafi guarantees to leave Libya but has yet to receive a reply.

Fresh NATO-led strikes sent up plumes of smoke in Tripoli yesterday, but US Defence Secretary Robert Gates warned the air war Gaddafi's forces could be in peril because of military shortcomings.

In a military update on Friday’s strikes, the British defence ministry said its fighters had destroyed four tanks ‘hidden in an orchard’ near the town of Al-Aziziyah, southwest of Tripoli.

Tornado and Typhoon jets also bombed a military base at Al-Mayah on the western outskirts of the capital, it said.

Turkish Prime Minister Recep Tayyip Erdogan said his government had offered exit ‘guarantees’ to the embattled Libyan leader, whom rebels have been trying to oust since February following a bloody crackdown on pro-reform protests.

Gaddafi ‘has no other option than to leave Libya - with a guarantee to be given to him,’ Mr Erdogan said on NTV television.

‘We have given him this guarantee. We have told him we will help him to be sent wherever he wants to go,’ he added, without elaborating.

‘Depending on the reply we will get from him, we will take up the issue with our (NATO) allies, but unfortunately we have received no reply so far.’

Col Gaddafi's daughter filed a second war crimes complaint against NATO and France in Paris on Friday over air strikes that killed family members including three infants, her lawyer said.

Aisha Kadhafi filed a similar complaint in Brussels on Tuesday over an April 30 assault on Tripoli, which, according to Libyan officials, killed Col Gaddafi's youngest son and three grandchildren.