Libyan government soldiers battled anti-Gaddafi fighters on the road to the insurgent stronghold of Benghazi on Thursday as the United States raised the possibility of air strikes to stop Muammar Gaddafi's forces.
The army told people to leave opposition-held locations and arms dumps. But its advance on Benghazi - and the prospect of a decisive battle in the insurrection - was hampered by clashes around Ajdabiyah, a strategic town on the coastal highway.
Slow-paced international efforts to halt the bloodshed moved up a gear when the United States, previously cool on the idea of a foreign military intervention, said the UN Security Council should consider actions beyond a no-fly zone over Libya.
"We are discussing very seriously and leading efforts in the Council around a range of actions that we believe could be effective in protecting civilians," US Ambassador to the United Nations Susan Rice said in New York.
"The US view is that we need to be prepared to contemplate steps that include but perhaps go beyond a no-fly zone."
Washington had initially reacted cautiously to Arab League and European calls for a no-fly zone over Libya, with some officials concerned it could be militarily ineffective or politically damaging.
Diplomats told Reuters that the United States, Britain and France now supported the idea of the council authorizing military action such as airstrikes to protect civilian areas.
Russia, however, and other council members are resisting the proposals.
The change appeared to driven by the increasing plight of the rebels, who are fighting to end 41 years of rule by Gaddafi.
Their ill-equipped forces have been driven back by troops backed by tanks, artillery and war planes from towns they had seized last month in the early days of the uprising.
A message on Al-Libya state television told people in Benghazi, seat of the insurgents' provisional national council, that the army was coming "to support you and to cleanse your city from armed gangs."
"It urges you to keep out by midnight of areas where the armed men and weapon storage areas are located," it said.
Benghazi residents poured scorn on the army announcement and said the eastern city was quiet.
Jibril al-Huweidi, a doctor at al-Jalaa Hospital in Benghazi, said ambulances were shuttling between there and Ajdabiyah, 150 km (90 miles) to the south on the Gulf of Sirte.
"They could not have made it repeatedly back and forth tonight if the evil forces were closing in on Benghazi," he said.
Muammar Gaddafi said on Lebanon's LBC TV he did not expect a battle in Benghazi because Libyan people have been helping get rid of "al Qaeda" elements there - repeating his contention that the rebels are linked to the Islamist militant organisation.
One of Gaddafi's sons, Saif al-Islam, had told Euronews TV on Wednesday morning that Libya's second largest city would fall whether or not the international community agreed to impose a no-fly zone. "Everything will be over in 48 hours," he said.
Aid agencies the International Committee of the Red Cross (ICRC) and Medecins Sans Frontieres have withdrawn their workers from Benghazi due to safety concerns.
But Libyan rebels fought back against Gaddafi's troops around Ajdabiyah, hampering their advance.
One rebel officer said on Wednesday morning the town had been lost and the fighters who remained had handed over their weapons. But on Wednesday evening, residents said the rebels held the centre of town while government forces were mostly on its eastern outskirts.
In New York, anti-Gaddafi Libyan diplomat, Ibrahim Dabbashi, told reporters that foreign powers had ten hours to act against Gaddafi's troops.
"We think that...in the coming hours, we will see a real genocide in Ajdabiyah if the international community does not move quickly and prevent him from attacking it with a large force," he said.
A rebel spokesman in Benghazi, Mustafa Gheriani, told Reuters by telephone that they were holding Ajdabiyah.
"But the fighting is fierce. His supply lines are stretched so he can't push on from Ajdabiyah. We've got some surprises in store. We're going to fight on and we're going to win.