Khartoum: Clashes between troops and rebels in Sudan's war-torn state of South Kordofan killed dozens of people, UN and rebel sources said, with an NGO worker reportedly among the dead.

Rebels from the SPLM-North attacked a checkpoint in the Kurgul area, around 35 kilometres south of Deleng, reportedly killing 12 Sudanese soldiers at around 1100 IST, a UN source said requesting anonymity.

Three vehicles were caught in the crossfire, including two private buses and a car belonging to an international NGO, in which a Sudanese staff member was killed and his driver seriously wounded, the source added.

The road, the main land route to South Kordofan state's capital Kadugli, runs through a mountainous area known to host SPLM-North rebels.

Fighting between the Sudanese Army and SPLM/A militiamen in South Kordofan broke out in June, just one month before the independence of South Sudan.

Separate clashes indicate that four months later the conflict, which was apparently triggered by the Army's insistence on disarming SPLA elements, is still intense.

Earlier, the rebels and the Army reported heavy fighting in the state's eastern Rashad district, with both claiming to have killed dozens on the opposing side.

Khartoum has sought to reassert its authority within its new borders since South Sudan's recognition as the world's newest nation on July 9, moving to disarm troops outside its control.

South Kordofan and Blue Nile, where a similar conflict broke out on September 2, are located just north of Sudan's new international border.

But they both have large numbers of SPLM-North supporters and troops, who have historic political ties to Khartoum's former civil war enemies, now the ruling party in Juba.

(Agencies)