Libyan leader Moamar Gaddafi is ready to unleash the full might of his forces to crush a three-week-old insurrection, his son said

Libyan leader Moamar Gaddafi is ready to unleash the full might of his forces to crush a three-week-old insurrection, his son said overnight, as warplanes and tanks struck at the country's rebel-controlled east.

"It's time for liberation. It's time for action. We are moving now," Saif al-Islam told Reuters in an interview. "Time is out now ... we gave them two weeks (for negotiations)."

As he spoke, Gaddafi's forces intensified their counter-attack on the insurgent heartland, bombarding rebel positions in the oil port of Ras Lanuf. Warplanes also hit Brega, another rebel-held oil hub further east.

State television said the army had driven the rebels out of Ras Lanuf, just behind their frontline but the rebels denied it.

In Brussels, NATO defence ministers resisted calls for a no-fly zone to help the beleagured rebels.

NATO secretary-general Anders Fogh Rasmussen told a meeting any military action could happen only with a demonstrable need, a clear legal basis, and firm regional support, not all of which now apply.

Defence ministers decided instead to step up surveillance of Libyan air space and to move warships closer to the Libyan coast.

But Mr Rasmussen said a no-fly zone was still a possible next step and that NATO forces will be monitoring the arms embargo against Libya.