On the front line, rebel fighters had pulled back from the town of Ras Lanuf, where an oil refinery was still in flames and Libyan leader Muamer Gaddafi's forces appeared to be in control, AFP reporters said.
Arab League Secretary General Amr Moussa also called for a no-fly zone and said he wants the pan-Arab organisation to play a role in imposing it, in an interview published Saturday.
"The United Nations, the Arab League, the African Union, the Europeans -- everyone should participate," Moussa told German weekly Der Spiegel
"I am talking about a humanitarian action. It consists, with a no-fly zone, of supporting the Libyan people in their fight for freedom against a regime that is more and more disdainful."
Moussa said Gaddafi was showing a lack of the "awareness that presidents Zine El Abidine Ben Ali in Tunisia and Hosni Mubarak in Egypt demonstrated by resigning" and predicted more revolts in the Arab world.
An opposition member, Slimane Mbarek, said on Saturday rebel delegates had handed Moussa a letter urging the Arab League "to end the bloodletting through a decision to impose an air-exclusion zone on Libya and recognising the transitional national council as the representative of Libya."
Hisham Youssef, Moussa's chief of staff, said earlier that two envoys from Tripoli would be barred from the meeting in line with the March 2 decision of the 22-member bloc to suspend Libya.
The meeting of foreign ministers and other representatives would discuss "the developments of the situation in Libya to find ways to end the bloodshed in Libya," Youssef said.
EU leaders agreed at an emergency summit Friday to talk to Gaddafi's opponents and protect Libyan civilians "by all necessary means" while stopping short of an outright military threat.
They demanded Gaddafi "relinquish power immediately" and deemed the opposition council based in the eastern city of Benghazi "a political interlocutor."
However, there was no mention of calls from Britain and France for a no-fly zone, and strident demands from French President Nicolas Sarkozy for "targeted action" against Gaddafi went unheeded.
Four rebels in the village of Uqayla, on the east-west coastal road between Brega and Ras Lanuf, said they had pulled out of Ras Lanuf after fierce fighting since government forces stormed the town on Thursday.
AFP journalists advanced 15 kilometres (nine miles) further west towards Ras Lanuf and could see heavy smoke rising from an oil refinery that was hit in a Friday air strike, but no sign of either rebel or regime forces.
The fall of Ras Lanuf followed that of the western city of Zawiya, where Gaddafi's troops fired in the air Friday to celebrate the capture of the rebel stronghold, which put up a fierce two-week resistance.
The country's oil chief Shukri Ghanem told AFP operations had resumed at a key refinery in Zawiya which supplies the capital and western Libya.
In eastern, rebel-held Benghazi, up to 10,000 people poured into the streets on Friday in a carnival-like atmosphere, calling for Gaddafi to go and praying for victory.
A UN mission was due in Libya on Saturday to evaluate the country's humanitarian needs, Deputy Foreign Minister Khaled Kaaim said in Tripoli.
He said the mission would tour hospitals to check on food and medicine supplies, adding that six months' supplies of both were in stock.
Kaaim made no mention of the arrival of former Jordanian foreign minister Abdul Ilah Khatib, who is being dispatched by United Nations chief Ban Ki-moon to raise international concerns about Kadhafi's deadly crackdown on protests.
Khatib, due in Tripoli early next week, would put across to the regime "in no uncertain terms the concerns of the United Nations and the international community," Ban told reporters in New York.
The envoy would have a political role in trying to end the conflict but also to try to open up humanitarian access to the Libyan population, Ban said.
Khatib will be accompanied by senior UN humanitarian officials, UN political advisers and aides to the UN High Commissioner for Human Rights.
US President Barack Obama said Friday the world was "tightening the noose" on Gaddafi, but acknowledged he was "concerned" the Libyan strongman could thwart rebels battling to oust him.
Obama announced he would appoint an envoy to Libyan opposition forces as part of a bid to "change the balance" of the military situation in Libya, and warned the world had an obligation to avoid a massacre.
The president added he was gauging support with regional powers for a no-fly zone, which Washington has so far resisted.
The European Union also stressed the need for "a clear legal basis and support from the region", reflecting divisions over the advisability of military intervention.
The EU statement also called for an urgent summit on the crisis grouping the EU, the Arab League and the African Union, which on Friday rejected military intervention.
"We're going to have to continue to apply pressure," Obama said, as the US Treasury Department hit another nine Gaddafi associates with sanctions, including his wife Safia Farkash and his defence minister.
Libya's former ambassador to the UN, Abdel Rahman Shalgam, said US Secretary of State Hillary Clinton would meet Mahmud Jibril, the opposition national council's foreign affairs chief, in Paris on Monday.