NATO pounds Libyan naval ships

In a statement, a spokesman said Nato had to take "decisive action" given Col Gaddafi's increasing use of naval assets to launch attacks on civilians.

Flames and smoke could be seen rising from vessels hit in the capital's port.

Meanwhile, the Libyan rebel leadership has appealed for international help for towns in the mountains west of Tripoli.

The alliance statement said the use of indiscriminate mining by pro-Gaddafi maritime forces had disrupted the flow of much-needed aid into Libya and had also "demonstrated a clear intent to attack Nato forces".

It said the strikes on Friday demonstrated Nato's "resolve to protect the civilian population of Libya, using appropriate and proportionate force".

"All the vessels targeted last night were naval warships with no civilian utility," said Rear-Adm Russell Harding, Deputy Commander of Nato's mission in Libya.

It was unclear if there were any casualties.

The Nato air strikes are being carried out under a UN mandate to protect civilians from the forces of Col Gaddafi, who is trying to crush the three-month-old uprising.