Rebels in Sudan's main oil-producing state claimed Saturday to have destroyed four tanks during fighting near the state's capital, drawing a denial from the country's army.

Fighting has raged across the South Kordofan border state since June, stoking tensions between Sudan and its old civil war foe South Sudan and complicating talks over the oil industry, the disputed Abyei territory and other unresolved issues.

Qamar Dalman, spokesman for the insurgent Sudan People's Liberation Army-North (SPLA-N) in South Kordofan, said rebel fighters engaged Sudan's army Friday near the town of al-Hamra in an area about five kilometres from the state capital, Kadugli.

The SPLA (in South Kordofan) destroyed four modern tanks and a large number of military vehicles in fighting throughout the day yesterday in the area of al-Hamra, he said in an emailed statement.

Al-Sawarmi Khalid, Sudan's army spokesman, denied the claim, saying the area was quiet. There is not any fighting in the al-Hamra area, he said.

Both sides claimed to have killed hundreds of their opponents in heavy fighting near the town of Taludi further to the south Monday.

Sudan's army said it repulsed the attack, while the rebels have claimed to continue to advance on Kadugli -- a potentially major prize for the insurgents if it is taken.

Events in the state are difficult to verify independently because access for journalists is limited.

STRAINED TIES

Thousands of fighters in the South Kordofan and Blue Nile border states sided with the south during Sudan's decades-long civil war, but were left north of the border when South Sudan became independent in July.

Both Khartoum and Juba have accused the other of backing rebels on their side of the border, and both have denied the others' claims.

Sudan's army pushed rebels out of their Blue Nile stronghold of Kurmuk Thursday, although insurgents there vowed to continue fighting.

Dalman also accused Khartoum of arming tribes to fight rebels in South Kordofan, echoing accusations in other Sudan conflicts such as the western Darfur region that the government has denied.

South Sudan seceded after voting overwhelmingly for independence in a January referendum promised in a 2005 peace deal that ended one of Africa's longest and deadliest civil wars.

Border violence since then has worsened ties between Sudan and Western powers. U.S. President Barack Obama extended trade sanctions this week that have been in place since 1997.

(Reporting by Khaled Abdelaziz and Alexander Dziadosz; Editing by Sophie Hares)