Clashes between Sudan’s army and rebels in the state of South Kordofan, bordering South Sudan, erupted on Monday after a week of relative calm in the oil-rich region which has been torn by violence since June last year.

South Kordofan Governor Ahmed Haroun told reporters that 12 rebels and four civilians were killed during a fight between Sudanese army and insurgents in the eastern part of the state.

“The army delivered a serious blow to the rebel forces, killing 12 insurgents, injuring dozens and taking one prisoner,” Haroun said, adding that three grenade launchers and large amount of ammunition had been seized after the skirmish.

Last week, rebels from the Sudan People's Liberation Movement-North (SPLM-North) shelled South Kordofan's main city Kadugli, killing six and injuring 22 people, mainly women and children.

The Sudanese army has been fighting SPLM-North militants in the states of South Kordofan and Blue Nile on the border with South Sudan for more than a year.

The border region has been engulfed in violence since South Sudan gained independence from Sudan in July 2011, after decades of civil war which is believed to have claimed the lives of more than two million people.

The SPLM-North rebels sided with the South against Khartoum during the civil war.

Sudan and South Sudan have repeatedly accused each other of supporting rebels seeking to unseat the governments in Khartoum and Juba until the two countries agreed in September to set up a buffer zone along the border and to stop backing rebels on both sides.

The indirect talks between Khartoum and SPLM-North, mediated by the African Union, have so far shown little progress.