Libya conflict: New fighting in town of Bani Walid
Seven anti-Gaddafi fighters have been killed and 10 wounded in a fierce battle for the town of Bani Walid.
The fighters say they were betrayed by local people who claimed to be on their side and led them into an ambush.
Nato is targeting the town, held by forces loyal to the fugitive leader, but the attackers lack the forces to capture it, a BBC correspondent says.
Meanwhile 15 guards were killed when pro-Gaddafi forces attacked an oil refinery near the town of Ras Lanuf.
An injured oil worker said a convoy of vehicles launched the surprise attack on the refinery - controlled by the anti-Gaddafi National Transitional Council (NTC) - after approaching from the direction of the fugitive leader's hometown of Sirte.
The refinery was not thought to be operational at the time.
In Tripoli, meanwhile, there has been an explosion at an arms dump near the international airport, the cause of which is unclear.
'Leading the struggle'
The attacks come a day after Col Gaddafi's son Saadi was given refuge in neighbouring Niger.
He is among 32 members of Col Gaddafi's inner circle - including three generals - who have crossed the expansive desert border into the central African nation since 2 September, Niger's Prime Minister Brigi Rafini told diplomats on Monday.
Mr Rafini said the Libyans had been taken in by Niger for "humanitarian reasons" and said none of those known to have crossed the border were being sought by the International Criminal Court.
The US state department said Niger confirmed they would detain Saadi Gaddafi in Niamey, the capital, but a spokesman for the Niger government said he was merely being watched.
"Nothing has changed in the government's position. There is no international search for him. Like the others he is just under surveillance," the spokesman told Reuters news agency.
Anti-Gaddafi troops now control most of Libya, including the capital Tripoli. Loyalists are holding out in at least three towns, including Bani Walid and Sirte.
On Monday, China became the last permanent member of the UN's Security Council to officially recognise the NTC as Libya's "ruling authority", state media reported.
Xinhua's report of the announcement ended weeks of uncertainty about when China would endorse the anti-Gaddafi forces.
Correspondents say the move further isolates Col Gaddafi, whose whereabouts are unknown. In recent audio broadcasts he has insisted he will die in Libya.
A new message was aired by the Syrian-based Arrai TV channel on Monday, in which Col Gaddafi described the opposition forces in Libya as traitors and said he would fight against the "coup".
However, whereas previous messages were audio recordings of Col Gaddafi, this was a statement read out on air.
Arrai's owner, Mishan Jabouri, said Col Gaddafi was still "leading the struggle from Libyan lands, and not from Venezuela, Niger or anywhere else," but that security reasons meant he could not read the message himself, Reuters reports.
The BBC's Richard Galpin, near Bani Walid, says the battles already underway for Sirte and Bani Walid are proving a lot tougher than the anti-Gaddafi forces had expected.
Fighting in Bani Walid was halted on Monday, with one commander telling the BBC they were waiting for Nato warplanes to continue their airstrikes, which are targeting the heavy weapons being used by Col Gaddafi's men inside the town.
Dozens of cars are streaming out of the town in anticipation of an assault.
Families fleeing the town say the streets are deserted with people either staying inside their homes or leaving. The shops are all closed and there is a shortage of food, they say.
Resident Fadila Salim told the Associated Press news agency that she was leaving because she was told "the fighting will be very bad".
The attackers are hopeful that if they can secure Bani Walid, the other loyalist strongholds will fall more quickly.