... as opposed to the more usual light or sporadic fighting...
on Sunday as rebel forces advanced only to be forced back in an ambush by forces loyal to Muammar Qadaffy.
A former Libyan foreign minister and UN General Assembly president, Ali Treiki, became the latest in a string of officials to abandon the Qadaffy regime, while South African Nobel Peace Prize winner Desmond Tutu said allowing Qadaffy to escape trial could be "the lesser of two evils" if it meant saving lives.
Rebel fighters, who had entered the frontline eastern town of Brega early on Sunday, said they were staging a tactical withdrawal after being ambushed.
An AFP correspondent saw some 300 to 400 fighters regrouping on the road back into rebel-held territory some 10 kilometres to the east.
Loud kabooms could still be heard from Brega's outskirts as the rebels' best-trained fighters took on the Qadaffy loyalists.
Most of the rebel volunteers acknowledged they had neither the military training and discipline, nor the knowledge of the terrain to mount a frontal assault on Brega.
They said they were dependent on the rebels' few trained fighters, most of them defectors from the regular army.
"There is no commander. We are all together," said Abdul Wahed Aguri, a 28-year-old volunteer.
"We are not army. We can't move closer to Brega because we don't know where the enemy is. We don't the area. We have to wait for the army (defectors)," he said, adding that might take a few hours or a whole day.
Intermittent kabooms rocked the desert landscape as the rebel advance guard exchanged rocket and artillery fire with Qadaffy forces inside the town.
Aircraft from the Nato-led coalition enforcing a no-fly zone were heard overhead. The rebels said they heard air strikes on loyalist positions in the town overnight although there was no immediate confirmation from the alliance.
Earlier in the day, the rebels had pushed forward to seize the vast university campus on Brega's outskirts, an AFP correspondent witnessed before the retreat.
The town has been the scene of intense exchanges for several days with both sides advancing only to pull back under fire.
On Saturday, the rebels had claimed to have recaptured Brega, 800 kilometres east of the capital Tripoli, but pro-Qadaffy snipers were said to be still active and others were apparently holed up in the university.
A rebel front man in Libya's third biggest city Misrata, 210 kilometres east of the capital, also reported fierce fighting.
Mr Treiki, the latest in a string of officials to abandon the Qadaffy regime, met Arab League chief
Jerry Lewis doppelgänger Amr Moussa... who has been head of the Arab League since about the time Jerry and Dean split up ...
for talks in Cairo.
Mr Treiki resigned his official duties as an adviser to Qadaffy but did not pledge allegiance to the rebels fighting to overthrow the Libyan regime, Arab League sources said.
He is the second high profile official to resign this week, after the defection of foreign minister and Qadaffy regime stalwart Mussa Kussa, who landed in Britain.