BENGHAZI, Libya – A defiant Muammar Gadhafi vowed to fight until victory as his forces launched surprise fightbacks on three fronts on Monday, and as Libya's interim government won recognition from China.

The ferocious counterattacks on a Ras Lanuf oil refinery, near Gadhafi's hometown of Sirte, and at Bani Walid near Tripoli came as a US official said Niger was ready to detain one of the elusive leader's sons, Saadi, after he fled over the border.

"It is not possible to give Libya to the colonists again," and "all that remains for us is the struggle until victory and the defeat of the coup", Gadhafi said in a statement read out on Syria-based Arrai Oruba television.

Gadhafi has gone underground since being ousted from Tripoli late last month, and Libya's new interim leader, Mustafa Abdel Jalil, received a hero's welcome in the city's main square.

A crowd of thousands celebrated victory against Gadhafi's in Martyrs' Square, two days after Abdel Jalil, the head of the National Transitional Council (NTC), arrived in Tripoli from the former rebels' eastern stronghold of Benghazi.

Jalil told the crowd Islam will be the main source of legislation in post-Gadhafi Libya.

"We will not accept any extremist ideology, on the right or the left. We are a Muslim people, for a moderate Islam, and we will stay on this road," he said.

NATO vowed no let-up in its bombing campaign against Gadhafi's remaining strongholds, which also include the southern oases of Waddan and Sabha, as long as they pose a threat.

China, which opposed the NATO air strikes which began in late March, became the latest country to recognise the NTC as Libya's government, the state-run Xinhua news agency reported.

"China respects the choice of the Libyan people and attaches great importance to the status and role of the NTC, and has kept in close contact with it," the state-run Xinhua news agency quoted foreign ministry spokesman Ma Zhaoxu as saying in a statement.

And Washington sent an advance team of four troops to help its officials reopen the US embassy in Tripoli.

But forces loyal to the fugitive Gadhafi sprang a surprise deep behind enemy lines, killing at least 12 NTC soldiers in a raid on the refinery near Ras Lanuf on the central coast.

"So far, we have a figure of 12 dead in the ranks of the revolutionaries" guarding the key plant, military spokesman Mohammed Zawawi said.

"A group (of loyalists) travelling in five vehicles tried to enter the refinery but were unable to," he said.

The oil infrastructure along the Mediterranean coast between Sidra and Brega was a key battleground of the seven-month uprising against Gadhafi, and the front line between the mainly rebel-held east and mainly government-held west went back and forth several times.

But since Tripoli's fall, NTC forces have advanced dozens of kilometres west towards Sirte, which remains in Gadhafi's hands, and have moved to secure the vital oil infrastructure on which its post-war reconstruction plans depend.

In its latest update, NATO said warplanes had hit 13 targets in and around Sirte, four around Waddan and one near Sabha.

NATO chief Anders Fogh Rasmussen said the strikes would go on until the threat to civilians had been eliminated. -- AFP