Libyan rebels say they have regained control of the oil town of Brega, hours after Libyan leader Muammar Gaddafi's troops had seized it.
Rebel Colonel Hamed al-Hasi, a rebel spokesman in Brega, told Al Jazeera on Sunday: "We have captured 20 of Gaddafi's forces and we killed 25. We have forced them to retreat 20km from the town."
However, the rebels say they are under heavy air attack by the Libyan air force.
Earlier on Sunday Libyan forces loyal to Gaddafi said they had cleared "armed gangs" from Brega, according to Libyan state television.
Gaddafi loyalists have also reportedly taken control of Ras Lanuf, another key oil hub, after bombarding the area from the land, sea and air.
Over the last weeks' fighting, both sides have frequently claimed victory in battles over towns long before any decisive action.
Pro-Gaddafi forces have been swiftly advancing on the poorly equipped and loosely organised rebels who had seized much of the eastern parts of the country since the uprising against Gaddafi's decades-long rule began last month.
The government says that all oil ports are now under its control. Rebel fighters are moving further east to Ajdabiya.
Ajdabiya is still under rebel control but has been under constant attack by Gaddafi loyalists.
It is the only other major population centre between Gaddafi's forces and the rebel headquarters in Benghazi.
If his successes continue, the Libyan strongman will soon face the choice of consolidating his control of the Mediterranean coast or moving swiftly toward Benghazi and the prospect of a devastating battle.
"Benghazi doesn't deserve a full-scale military action,'' army spokesman Milad Hussein said in the capital, Tripoli.
"They are a group of rats and vermin and as soon as we go in, they will raise their hands and surrender.''
Pro-Gaddafi forces are also besieging the western Libyan towns of Misurata and Az-Zawiyah, only the strongholds of Benghazi and Tobruk remain firmly in the grip of the opposition.
Abdel Fattah Ahmed, a political activist from Misurata, told Al Jazeera that the city is under heavy attacks by pro-Gaddafi forces stationed around the city.
He said that bombardment is ongoing and random and that some homes have been hit.
Apart from defectors from Gaddafi's army, the rebels have no military experience, few heavy weapons and they are virtually powerless against air attacks.
Al Jazeera's Tony Birtley, reporting from the rebel stronghold of Benghazi, said: "We have to remember that this is not an organised army. This is a group of teachers, engineers, street cleaners - people who have had no association with weapons whatsoever.
"And now they're coming up against very strong, well-equipped forces. And we are seeing a lot of casualties. Basically if it is not sorted out soon, then those casualty figures are going to go up and up and up.
"It's not a very good situation at the moment; it is not looking very positive, quite the reverse."
The rebels have been pleading for Western powers to protect them with a no-fly zone, and on Monday their leaders are due to meet in Paris with US Secretary of State Hilary Clinton, who plans to assess their capabilities and intentions.
The Arab League asked the UN Security Council on Saturday to impose a no-fly zone. But the US and many allies have expressed deep reservations about a tactic that would require them to destroy Gaddafi's air defences and possibly shoot down his planes, and they appeared no closer on Sunday to imposing a no-fly zone.
Libya responded to the Arab League resolution calling it "an unacceptable departure" from the body's charter, state television said on Sunday.
Source: Al Jazeera and agencies