It said the operation was intended to stop "inflammatory broadcasts" by Col Muammar Gaddafi's regime.

NATO said it was in the process of assessing the effect of the strike.

Coalition forces began operations in Libya in March, under a UN mandate authorising military action for the protection of civilians.

Libyan rebels began an uprising against Col Gaddafi in February. Despite NATO's intervention, they have struggled to break a military deadlock.

A NATO statement said the strike was "performed by NATO fighter aircraft using state-of-the-art precision guided munitions", and that there had been "due consideration and careful planning to minimise the risks of casualties".

"Our intervention was necessary as TV was being used as an integral component of the regime apparatus designed to systematically oppress and threaten civilians and to incite attacks against them," it said.

It said the strike would "reduce the regime's ability to oppress civilians" but also "preserve television broadcast infrastructure that will be needed after the conflict".

Libyan state TV was still on air following the NATO statement.

Reports from Tripoli said a series of loud explosions were heard in the city centre late on the evening of July 29.

Libyan state TV reported that civilian targets had been hit, though this could not be verified.

The Libyan capital has been a regular target for NATO air strikes in recent weeks.