Fighting has broken out between government forces and rebels in central Sudan, both sides said on Sunday, in a possible escalation of violence that has hitherto been concentrated closer to the African country's borders.
Rebels of the Justice and Equality Movement (JEM) from the western region of Darfur said they had launched an attack on the army in North Kordofan state.
JEM and two other Darfur rebel groups formed an alliance with a rebel group from southern Sudan, the SPLM-North, in 2011 to try to topple veteran President Omar Hassan al-Bashir.
Fighting with the army has been so far mainly limited to Darfur as well as South Kordofan and Blue Nile states bordering South Sudan, which seceded from Sudan in 2011.
The state of North Kordofan is closer to the Sudanese capital Khartoum and a large producer of gum arabic, a substance extracted from acacia trees used by the food and drinks industry and an important sources earnings for cash-strapped Sudan.
JEM said it had seized the western area of Wad Bahr in North Kordofan from government forces on Saturday. "We beat the army and seized many weapons," JEM spokesman Gibril Adam said.
Authorities confirmed the fighting but said the army and security forces had repelled the rebels who had been trying to "steal from citizens", according to the state-linked Sudanese Media Center (SMC).
"They suffered heavy losses," North Kordofan's governor Muattasim Mirghani told SMC, adding that the army had destroyed 12 rebels vehicles.
Sudan accuses South Sudan of supporting the rebel alliance, a claim denied by Juba. Both countries are locked in a long list of conflicts over border territory and oil rights that almost led to war between the neighbors last year.
South Sudan's army accused Sudan of having sent militias into the disputed region of Abyei, where peacekeepers monitor a ceasefire after fighting broke out in 2011.
"Villagers continued to be harassed and attacked by the pro-Khartoum government ... militia," South Sudan army spokesman Philip Aguer said late on Saturday.
"More than 200 cattle and more than that number of goats have been looted by the same militia," he said.
There was no immediate comment from Sudan.
In September, the African neighbors agreed to end hostilities and restart cross-border oil flows, the lifeline for both of their battered economies.
But neither side has withdrawn their armies from the border as agreed, a legacy of decades of civil war which ended with a peace deal in 2005 and paved the way for southern secession.
Fighters of the Sudan People's Liberation Movement-North (SPLM-North) used to side with the south during the civil war and now complain, like the Darfur rebels, of marginalization in Sudan.