Ex-southern rebel group the Sudan People's Liberation Movement said on Tuesday that unilateral security decisions in Khartoum were behind the latest fighting in South Kordofan and called for a joint accord.
"The (ruling) National Congress Party and the Sudanese army have taken a unilateral decision on security without consulting the SPLM. They are trying to disarm the SPLA (southern army). That is what triggered the situation" in South Kordofan, Yasser Arman told AFP.
Arman, who is a senior member of the SPLM's northern branch, was part of a joint security delegation appointed by the Sudanese presidency to try to defuse the escalating tensions in the north's oil-producing border state between the northern army (SAF) and the SPLA.
The delegation, which included senior NCP negotiator for security Yahia Hussein, visited the state capital Kadugli on Monday, the same day that clashes erupted there between troops from the two sides, after deadly unrest over the weekend.
"Without a joint agreement on security between the the SPLM north and the NCP it will be difficult to resolve this situation," Arman warned.
South Kordofan is a former civil war battleground that is awash with weapons and has strong links to south Sudan, especially among the indigenous Nuba peoples, who fought on the side of the southern rebels.
The south is due to achieve full independence on July 9 after voting almost unanimously to break away from the north in January's landmark referendum, the culmination of a 2005 peace accord that ended a devastating 22-year conflict.
Security is one of the main unresolved issues that the two sides have struggled to negotiate pre-independence.
Khartoum has ordered northern SPLA troops to either disarm or redeploy south of the 1956 borders beforehand, threatening unspecified consequences if they fail to do so.
Arman repeated earlier SPLM claims that the latest unrest in South Kordofan was prompted by a rebellion within the northern army, with a group of SAF troops in the 14th infantry division refusing to disarm the SPLA.
"Division 14 of the Sudanese army is mostly from the southern part of South Kordofan, and they don't want to fight their brothers from the Nuba Mountains. So there is discontent within the 14th division of the SAF."
Arman said there were more than 40,000 northern SPLA troops based in South Kordofan and Blue Nile state, the so-called transitional areas, including 6,000 men in the special Joint Integrated Units of northern and southern personnel.
He added that the joint delegation did not touch on the issue of last month's hotly disputed state election for the post of governor, saying: "we have to solve the security situation first."