Colombo  - The Sri Lanka Air Force bombed a Tamil rebel logistic base in northern Sri Lanka for a third-straight day after least 21 rebels were killed in clashes elsewhere, military officials said Friday.

Fighter jets on Friday pounded the logistic base, which also housed a vehicle parts and hardware supplies store, located at Vishvamadu, Mullaitivu, 320 kilometres north-east of Colombo.

The base was destroyed, said Wing Commander Janaka Nanayakkara, an air force spokesman.

As part of Friday's operation, air force MI-24 helicopters also bombed a forward rebel defence line in support of ground troops who were advancing into rebel-controlled areas.

The air raids took place close to the rebel stronghold of Thunukkai, 310 kilometres north-east of Colombo.

On Thursday, fighting was reported in the Weliloya, Mullaitivu, Vavuniya and Jaffna areas, where a total of 21 rebels were killed, military spokesman Brigadier Udaya Nanayakkara said.

Government troops backed by air support have been advancing into rebel-held areas and intensified operations since January when a ceasefire was officially scrapped.

Sri Lanka took control of the Eastern Province earlier this year and aims to take back the last remaining rebel stronghold in the north by the end of 2008.

Provincial elections are scheduled Saturday for two of the country's nine provinces. The government has called on voters in the North-Central and Sabaragamuwa provinces to elect the ruling United People's Freedom Alliance (UPFA) to support the ongoing military offensives against the rebels.

The military has claimed to have killed more than 10,000 rebels since April 2006 and to have lost 1,900 security personnel. However, there is no independent confirmation of the casualty figures. (dpa)