Sudan’s military denied the assertion, however, saying the region was quiet after the army repulsed a rebel attack on Tuesday.
Fighting along Sudan’s border with South Sudan has complicated talks over unresolved issues such as how to manage the formerly integrated oil industry, and analysts say it has threatened to drag the old civil war foes into a proxy conflict.
The countries have accused one another of backing rebel groups in areas near the border since South Sudan split off into a separate country in July.
Qamar Dalman, a spokesman for the rebel Sudan People’s Liberation Army-North (SPLA-N) in South Kordofan, said insurgents were continuing to advance on the town of Taludi on Wednesday.
“There is heavy fighting around Taludi between SPLA forces and the Sudanese army. The SPLA army is very close to the city. The Sudanese army is bombing from military planes,” he said by telephone.
Al-Sawarmi Khalid, Sudan’s army spokesman, dismissed the claim. “There is not any fighting or clashes today around Taludi. Everything is quiet,” he said.
Both sides claimed to have killed hundreds of their opponents during a rebel assault on Taludi on Tuesday, although neither report was possible to verify independently.
Conflict has torn South Kordofan and Blue Nile, both states on Sudan’s side of the border and home to tens of thousands of fighters who sided with the south during a decades-long civil war that killed some 2 million people.
Rebels say they have been politically and economically marginalised by Sudan’s government, while Khartoum accuses the insurgents of trying to spread chaos and says it will not tolerate armed rebel militias on its side of the border.
South Sudan seceded after voting for independence in a January referendum promised in a 2005 peace deal that ended one of Africa’s longest and deadliest civil wars.