Contacted by Reuters in the early hours, rebel fighter Ibrahim al-Alwani said he and comrades still in Ras Lanuf had seen government troops in the town center."I saw maybe 150 men and three tanks," he said. "I can hear clashes."

Another rebel reported clashes with Gaddafi troops who had landed in Ras Lanuf by boat.

West of Tripoli, street fighting was reported in Zawiyah, which has changed hands several times in recent days. Residents described scenes of carnage, with women and children among the dead.

Gaddafi's son Saif al-Islam told the rebels on Thursday they faced a full-scale assault to crush their three-week-old uprising. "It's time for action. We are moving now," he told Reuters in an interview. "Time is out now ... we gave them two weeks (for negotiations)."

As the military momentum appeared to turn against the rebels, foreign powers were at odds over how to end the turmoil.

Reuters