A counter-offensive during the past week has pushed rebel fighters out of Mediterranean coastal towns, allowing the regime to wrest back momentum against a month-long uprising.
Dozens of rebels have fled east out of the town of Brega towards Ajdabiya, the last rebel-held town before the city of Benghazi just 170km away.
The rebels have made Benghazi their de facto capital.
France, which alone has recognised the rebels' interim national council as the rightful representative of Libya, has called for a speeding up of the international push for a no-fly zone.
Meanwhile, the International Committee of the Red Cross says it has shipped seven truckloads of food and medicine from Jordan to Brega.
The charity Doctors Without Borders says rebels are being denied medical help in government-held areas.
Human Rights Watch says Libyan authorities have carried out a wave of "arbitrary arrests and forced disappearances" in the capital, Tripoli.
