BENGHAZI, Libya: Libya's rebels said a light mobile force had breached the strategically vital oil town of Brega late Friday, before pulling back in anticipation of a renewed offensive at daybreak.

Mohammed Zawi, a spokesman for the rebel army, told AFP a group of reconnaissance troops had entered the city from the north, then pulled back four kilometres (2.5 miles) before midnight (2200 GMT).

The probing raid deep into Qadhafi-held territory came around 32 hours after the rebel command launched a three-pronged attack to wrest control of the town back from Moamer Qadhafi's troops.

While the rebels' forward position to the north was four kilometres from the town centre, a second unit attacking from due east of Brega faced stiffer resistance and was about 10-20 kilometres (six to 12 miles) from the town.

“Most of Qadhafi's troops seem to be at the centre,” said Zawi.

To the south of the town, where the rebels had made initial gains but suffered large numbers of casualties, Qadhafi forces had pushed back harder.

With fighting in the dusty desert terrain difficult, Zawi said him expeced fighters on both sides to dig in for the night.

Rebels were also trying to dispose of more than 100 landmines placed around the town. “Tomorrow we can take Brega, God willing,” he said.

Brega, nestled at the southeastern tip of the Gulf of Sirte, has changed hands multiple times during Libya's civil war, which soon enters its fifth month.

In recent weeks the rebels have been holed up at a forward position 40 kilometres (25 miles) from both Brega and Ajdabiya, inching forward and clearing mines so their handful of T-72 tanks and infantry fighting vehicles can have a freer rein.

The town's vast oil refinery and storage facilities - if intact - could provide fuel and a much-needed income stream for the rebels.

A victory would also provide a major boost for rebel morale, which had been sagging amid months of stalemate.