Except for occasional rebel forays over the border from the conflict-plagued Darfur region, North Kordofan had been generally peaceful.
But on Saturday a rebel coalition struck a major North Kordofan town which residents said had been left unguarded and was hit during coordinated attacks in the insurgents' most audacious act in years.
"North Kordofan state has all become our target," Arnu Ngutulu Lodi, spokesman for the Sudan People's Liberation Movement-North (SPLM-N), told AFP.
Lodi said that insurgents yesterday shelled the airport area of Kadugli, the capital of South Kordofan, for the second time in two days.
More From This Section
He warned civil aviation to avoid the area, as well as the airspace in North Kordofan.
"It is becoming a target for us," Lodi said. "This is a very serious kind of warning. This whole area has become an operational area."
SRF said it attacked Umm Rawaba, the second-largest town in North Kordofan, and several other areas in North and South Kordofan as part of its strategy to reach the capital Khartoum and overthrow the 24-year regime of President Omar al-Bashir.
Speaking to troops in a state television broadcast, he said he wanted the area down to the South Sudanese border "cleansed of rebels".
The SPLM-N has shelled Kadugli periodically since late last year, but on Saturday for the first time targeted the airport region.
That barrage killed four soldiers, Lodi claimed, but residents reported only a few injuries.
They said they could not confirm that a second barrage occurred yesterday, and reported the town as calm today.
The government blamed rebels for killing civilians in its previous shellings of Kadugli, while rights groups have accused the Khartoum regime of indiscriminate aerial bombing elsewhere in the state.