Rebels said they arrested dozens of militiamen loyal to Moamer Kadhafi in their eastern bastion but suffered a blow Monday in Libya's west, losing a village at the foot of a key mountain range.
At least 63 people suspected of having links to Kadhafi and of murdering the rebels' military chief were rounded up by the insurgents, following an hours-long battle in the opposition stronghold of Benghazi.
But in the west, pro-Kadhafi forces were again in control on Monday of the village of Josh at the foot of the strategic Nafusa mountains, AFP journalists at the scene said.
Josh had been emptied of its residents, the rebels said.
The rebels had on Sunday taken the village, but said they were forced to retreat to the east, half way along the road to the town of Shakshuka, after several hours of fighting.
The Nafusa region has seen heavy fighting between rebels and forces loyal to Kadhafi since the insurgents launched a major offensive this month in a drive on the capital Tripoli.
In Benghazi, opposition forces patrolled the streets in a bid to track down more members of the pro-Kadhafi group, a rebel spokesman said, as shoppers stocked up ahead of Ramadan, the Muslim holy month of fasting.
"We caught about 38 and later today more than 25," the spokesman, Mustafa al-Sagazly, told AFP late on Sunday.
"Some of them ran away and we are trying to catch them all over the city," he said. "We are arresting them."
The arrests came hot on the heels of a five-hour raid by the rebel-backed February 17 brigade on a Benghazi factory, leaving four rebels and five Kadhafi loyalists dead.
The fierce shootout erupted at around dawn on Sunday during a raid on the cell holed up inside a licence plate-making factory.
Rebel spokesman Mahmud Shammam said the group had been rounded up for its role in organising a prison break in Benghazi earlier in the week.
The pro-Kadhafi cell "had plans to plant car bombs in Benghazi," according to Mustafa al-Sagazly, deputy chief of the February 17 brigade.
He added the "very same group" -- the Katiba Yussef Shakir -- was suspected in the assassination of General Abdel Fatah Yunis, a right-hand man to Kadhafi before his defection to the rebel ranks.
Ismail al-Salabi, who heads military operations for February 17, called the operation "100 percent successful" and added the rebels seized TNT explosives and several pickup trucks equipped with machine guns.
Meanwhile British Defence Secretary Liam Fox said the murder of Yunis, attributed by the British press to Al-Qaeda elements within the rebel movement, remained a mystery and that militant influence within Libya was inevitable.
"It's not yet clear who actually carried out the killing," Fox said told BBC radio.
"Of course there are going to be militants in Libya -- there are militants right across the whole of the Middle East -- it would be a great surprise if there weren't some in Libya itself," he added.
Britain last week recognised the Benghazi-based opposition National Transitional Council (NTC) as Libya's legitimate government, and Fox vowed Britain would continue to back the group despite the assassination.
While the rebels have been trying to quash rumours about the mysterious death of their army chief, the Kadhafi regime said it was in contact with members of the NTC.
South of Benghazi, rebels reported an attack by pro-Kadhafi forces on the southern oasis town of Jalo, but said it had been repulsed.
Rebels also promised a "surprise" in the strategic oil hub Brega.
"We are in the suburbs of Brega and I can see its lights sparkling in the short distance. Expect a surprise," said Salabi.
On the western front in the five-month-old armed revolt, rebels on Sunday took the village of Josh at the foot of the Nafusa mountain range, but loyalists seized it back on Monday, AFP journalists at the scene said.
The Nafusa region has seen heavy fighting between rebels and forces loyal to Kadhafi since the insurgents launched a major offensive this month in a drive on Tripoli.
NATO said its warplanes carried out 49 strike sorties on Sunday, with hits concentrated in and around Zliten and Bir al-Ghanam. Strikes were also conducted in Tripoli, Brega and Waddan.
France said on Sunday it was committed to striking Kadhafi's military assets for as long as needed for him to quit power, and called on Libyans in Tripoli to rise up against him.
"We say to Kadhafi that we will not ease our pressure and to his opponents that we will not abandon them," French Defence Minister Gerard Longuet was quoted as saying by the newspaper Le Journal du Dimanche.
"Things have to move more in Tripoli... the population must rise up," he added.