Libyan rebels have entered the northwestern town of Yafran, previously held by Muammar Gaddafi's forces, reports say.
Youssef Boudlal, a Reuters photographer in the town, on Monday said the town had been wrested by the rebels.
"We are inside the town ... There is no sign of any Gaddafi forces. I can see the rebel flags ... We have seen posters and photos of Gaddafi that have been destroyed," he said.
Al Jazeera's Cal Perry, reporting from the rebel stronghold of Benghazi in eastern Libya, said it was not clear what tilted the balance in the rebels' favour in Yafran.
"We do not have details of what provided this breakthrough...this is a town that has been held by Gaddafi forces since the start of the fighting.
"It is really unclear where the Gaddafi forces have gone, and it is also unclear if it was a result of the NATO air strikes or use of the Apache helicopters," he said.
The rebel advance came amid continuing fighting between forces loyal to Gaddafi and rebels seeking to end his more than four-decades-long rule, inspired by uprisings in Tunisia and Egypt that toppled entrenched rulers.
Explosions in Tripoli
The rebels have been buoyed by NATO air strikes targeting Gaddafi forces. The military alliance has deployed attack helicopters for precision attacks, boosting rebels further.
Six powerful explosions were heard in the Libyan capital, Tripoli, as NATO warplanes flew over the city.
A powerful but distant blast was felt in the centre of the city at around 9:00pm (1900 GMT) on Sunday, followed by stronger explosions a few minutes later, an AFP correspondent said, unable to immediately determine the targets.
NATO fighter jets earlier launched intensive air raids on the capital and its eastern suburbs.
A Libyan government official, speaking to the Associated Press news agency on condition of anonymity, said British jets had hit a military barracks in Tripoli, but there were no casualties.
The Tripoli explosions came as William Hague, the British foreign secretary, said there was no deadline for NATO's Libya operation, and Russia voiced concerns that the use of helicopters showed NATO was sliding towards a land campaign.
"We're not going to set a deadline. You're asking about Christmas and who knows, it could be days or weeks or months, [but] it is worth doing," Hague told an interviewer on BBC television on Sunday.
Hague, who held talks with Libyan rebel leaders in Benghazi on Saturday, ruled out putting ground forces, saying NATO would stick to the terms of a UN Security Council resolution passed in March to protect civilians.
"We will continue in that way, intensifiying what we're doing - the Apache helicopters are an example of that - but that's different from mission creep," he said.
"This is not mission creep, changing the nature of the mission, this is intensifiying what we are doing in order to make this mission a success."
Hague's trip came just hours after British Apache helicopters attacked forces loyal to Gaddafi. Hague held talks in Benghazi with the head of the rebel Transitional National Council, Mustafa al-Jalil. He also toured the city's landmark seafront as well as a medical centre treating war wounded.
"We're encouraging the National Transitional Council to put more flesh on their proposed transition - to lay out in more detail this coming week what would happen on the day that Gaddafi went - who would be running what, how would a new government be formed in Tripoli?" Hague told the BBC.
'For as long as it takes'
Hague earlier said Britain would support demining efforts in Misurata, the main rebel-held city in western Libya, and deliver "more equipment, uniforms, bullet-proof jackets" to rebel fighters.
"We have no combat troops in Libya," he said. But Britain, he said, would stand with the Libyan people "for as long as it takes".
"We could not, and did not, turn a blind eye when Gaddafi turned his forces against innocent civilians," Hague said.
"For as long as Gaddafi continues to abuse his people, we will continue and intensify our efforts to stop him."
Earlier, Russia, which is calling for a negotiated solution to the Libyan conflict, has expressed alarm over the use of helicopters by NATO, with Sergei Lavrov, the foreign minister, saying that the decision was "deplorable".
"We consider that what is going on is either consciously or unconsciously sliding towards a land operation," he said on Saturday.
NATO attacks on the Libyan military and government infrastructure have been occurring daily since March 31 in an operation that has just been extended for another 90 days.
The 18-country mission, led by the US, UK and France, has several core goals: enforcement of a no-fly zone, maintenance of an arms embargo, protection of civilians and facilitation of humanitarian assistance.