TRIPOLI - Fifteen guards were killed and five others seriously injured when a group of Muammar Gadhafi's loyalists stormed an oil refinery near the northern coastal town of Ras Lanuf early Monday morning, Qatar-based al-Jazeera television reported.

The oil refinery, about 20 km from Ras Lanuf, is not fully operational, the report said. ?

The report said that a convoy of vehicles approached the refinery from the southern desert and armed men aboard launched a surprise attack on the front gate of the refinery.

Libyan rebels have repulsed the assault and besieged the fleeing assailants in Ras Lanuf's industrial area, according to the report.

In a separate incident, massive blasts occurred Monday at an arms depot near the international airport south of the Libyan capital of Tripoli, leaving two people injured, a television channel run by Libyan rebels reported.

The channel quoted a rebel official as saying the explosions were an accident as the ammunitions were "badly stored."

On the battle front in Bani Walid, an oasis town south of Tripoli, three Libyan rebels were killed and four others wounded in fighting with forces loyal to Gadhafi, a rebel fighter told Xinhua Monday.

The rebels were poised to take over the town and other areas still held by Gadhafi's forces, after the deadline set by the National Transitional Council (NTC) for a peaceful surrender expired Saturday.