Libyans flash the victory sign in front of a Kingdom of Libya flag during a celebration rally at Martyrs' Square in Tripoli.

Ras Lanuf - Muammar Gaddafi loyalists killed 15 guards in an attack on an oil refinery on Monday in an apparent attempt to disrupt a drive by Libya's new rulers to seize the ousted leader's last bastions and revive the oil-based economy.

A Syrian-based television station said it would soon broadcast another message from the fugitive Gaddafi, who has issued regular battle calls to his followers in the three weeks since Tripoli was overrun.

The new ruling National Transitional Council (NTC) says that as long as Gaddafi remains on the run he is capable of attracting followers to a dangerous insurgency.

Witnesses to the refinery attack said the assailants damaged the front gate of the facility, 20km from the coastal town of Ras Lanuf, but not the plant itself, which is not fully operational.

About 60 staff were there at the time of the attack, according to one of two wounded survivors at a hospital where the dead were also taken.

Refinery worker Ramadaan Abdel Qader, who had been shot in the foot, told reporters that gunmen in 14 or 15 trucks had come from the direction of the Gaddafi-held coastal city of Sirte.

“We heard firing and shelling at around 9 in the morning from Gaddafi loyalists,” he said. Staff had been asleep.

The assault occurred only hours after the NTC announced it had resumed some oil production, which had been all but halted since anti-Gaddafi protests turned into civil war in March.

The interim council is struggling to assert its control over the entire country and capture a handful of stubbornly defended pro-Gaddafi towns.

Many senior NTC officials also see scooping up Gaddafi and the members of his family who are still on the run as crucial to finally declaring victory in the seven-month old war.

Gaddafi's son Saadi arrived in neighbouring Niger on Sunday after crossing the remote Sahara desert frontier. On Monday the US State Department said that the government of Niger had confirmed to it that it intended to detain the former soccer player.

But a Nigerien government spokesperson told Reuters that Saadi Gaddafi was only being watched for now.

“Nothing has changed in the government's position. There is no international search for him. Like the others he is just under surveillance,” the spokesperson said, referring to other Gaddafi loyalists who have recently fled to Niger.

Two other sons and Gaddafi's only biological daughter have fled to Algeria. One son is reported to have died in the war and three others are still on the run.

The NTC has said it will send a delegation to Niger to seek the return of anyone wanted for crimes.

Niger, like Algeria, has cited humanitarian reasons for accepting fugitives of the former government, but has promised to respect its commitments to the International Criminal Court, which wants to try Gaddafi, son Saif al-Islam and intelligence chief Abdullah al-Senussi for war crimes.

NTC forces, which seized Tripoli on August 23, said they were meeting fierce resistance on the fourth day of fighting for the Gaddafi-held desert town of Bani Walid, 150km southeast of the capital, and were edging towards Sirte.

Libya's economy is almost entirely dependent on oil, and restarting production is crucial to restoring the economy. Interim Prime Minister Mahmoud Jibril said on Sunday some oil production had resumed, but would not say where or how much.

Libya holds Africa's largest crude oil reserves and sold about 85 percent of its exports to Europe under Gaddafi. Western oil firms, including Italy's Eni and Austria's OMV, are keen to restore production.

Eni's chief executive told Reuters his priority was to restart gas exports via a pipeline from Libya to Italy by October or November. Resuming oil output was less urgent.

“We are by far the biggest player in Libya, both in oil and in gas, so I came here with the idea of 'back to normal',” Paolo Scaroni said during a visit to Tripoli. - Reuters