Nato has insisted that, for a no-fly zone to be set up over Libya, there would have to be clear legal grounds and strong regional support.

On the diplomatic front, there's been a gloomy assessment in Washington of the rebels' chances, but the UK and France have sought to ramp up the pressure on Colonel Gaddafi ahead of Friday's EU summit, saying the Libyan leader has "lost any legitimacy".

Matthew Price reports from Brussels.