Libyan warplanes launched air strikes on rebel forces in the east on Tuesday as the two sides faced off across a new front line close to major oil export terminals.

The battlefield has become mired in attack and counter-attack between the loose-knit rebel army of young volunteers and defectors and Libya's army in a buffer zone of barren desert and scrub between east and west.

Libyan rebels rejected overtures by a representative of Muammar Gaddafi to negotiate his exit as his grip on power is increasingly challenged.

There were three air strikes near rebel positions on the outskirts of the oil terminal of Ras Lanuf on Tuesday following similar attacks the previous day. No casualties were reported.

Immediately after the latest explosion, rebels began chanting "Allah akbar" (God is greatest).

"I confirm that we received contact from a Gaddafi representative seeking to negotiate Gaddafi's exit. We rejected this," a media officer for the rebel Libyan National Council, Mustafa Gheriani, told Reuters, adding:

"We are not negotiating with someone who spilled Libyan blood and continues to do so. Why would we trust the guy today?" said Gheriani for the council, which is based in Libya's second city of Benghazi where the uprising against Gaddafi began.

In fiery and defiant speeches, Gaddafi has vowed to fight on and has told his supporters he will never leave Libya and end his 41-year-old rule.

Al Jazeera television said the Libyan government denied having talks with the rebels.