Fighting broke out in the northern state on June 5 and has escalated to include artillery and warplanes. Over 60,000 people are believed to have fled the fighting, the United Nations said.
Both U.S. President Barack Obama and U.N. Secretary-General Ban Ki-moon have called for an immediate ceasefire in Southern Kordofan, where humanitarian groups fear a mounting death toll.
Northern military spokesman Al-Sawarmi Khaled told reporters the army would continue to fight militants around the state capital of Kadugli and elsewhere.
“We are continuing our military operations in the mountains around Kadugli up to this moment, until the rebellion stops,” he told reporters in Khartoum.
The United Nations urged north Sudan’s military to open up airspace over Southern Kordofan, saying a six-day closure was endangering its aid operations there.
“The ongoing closure of the airspace in Southern Kordofan by SAF (Sudanese Armed Forces) is dangerously hampering our humanitarian operations as thousands of internally displaced persons are in urgent need of emergency assistance,” U.N. Mission in Sudan spokesman Kouider Zerrouk said.
“It is vital that the government of Sudan acts immediately to ensure access to all airspace by U.N. flights to alleviate the growing suffering of those most affected by conflict.”
The London-based group Save the Children said in a statement 30,000 of the displaced were children “at risk of being separated from their families, traumatised and abused”.
Khaled dismissed charges the army was putting civilians in danger.
The fighting broke out at a sensitive time for Sudan, with the south due to become a separate country on July 9. Southerners voted to secede in a January referendum promised in a 2005 peace deal that ended decades of civil war.
Many of the fighters in Southern Kordofan are still referred to as part of the south’s army as a legacy of that conflict, though the southern military says they are no longer part of its forces.
Officials in the south’s dominant party have said the fighting in Southern Kordofan erupted after the northern army tried to disarm fighters there. Northern officials have accused southern-aligned groups of starting the fighting.
The government in Khartoum stands to lose around a third of its territory and up to three quarters of its oil reserves when Africa’s largest country becomes two states, but most of the terminals, pipelines and refineries are in the north.
The northern government’s oil minister said earlier that north Sudan hae agreed to accept transit fees from the south to export southern oil after July 9 but the two sides had yet to agree a price.