Sudan’s president declared a state of emergency in a state near the southern border with Ethiopia after clashes broke out between armed forces and a rebel group.
Omar al-Bashir also sacked the governor of Blue Nile state hours after the rebel Sudan People’s Liberation Army attacked police and soldiers with heavy weaponry, setting off a battle.
Sudan’s information minister, Sanaa Hamad, had said earlier that Sudanese government forces were in control of the area and that the military repelled a rebel advance on the town of Damzain.
Ms Hamad said in statement carried by the Sudan news agency that the rebels have ignored a ceasefire declared by Bashir.
She also accused South Sudan, which achieved independence in July, of supporting the rebels in violation of peace agreements.
United Nations secretary general Ban Ki-moon expressed concern at the eruption of fighting and urged the parties to immediately cease all hostilities, UN deputy spokesman Eduardo del Buey said.
The UN Security Council will hold consultations on Sudan and South Sudan next Thursday.