Sudanese rebels said they attacked five areas in North and South Kordofan states on Saturday, widening an anti-government offensive in one of their most audacious acts in years.
"This is a significant shift in the war in Sudan," Abdel Wahid Mohammed al-Nur, who heads a faction of Darfur's Sudan Liberation Army, told AFP.
"We are heading to Khartoum," he said. "This is not a joke."
Residents of Umm Rawaba, the second-largest town in North Kordofan, said rebels arrived Saturday morning on at least 20 vehicles for a brief occupation.
They fired their weapons into the air, causing panic, but met no initial resistance from security forces, townspeople said.
"We just saw some drones in the air," one resident said, adding that the insurgents looted the market.
Other residents said the town's inhabitants cowered in their homes as rebels shot at government buildings and policemen before withdrawing. It was not immediately known if there were casualties.
North Kordofan has been largely free from the rebel activity taking place in the Darfur region to its west, and South Kordofan to its south.
"This is part of our strategy to overthrow the regime," said Gibril Adam Bilal, spokesman for Darfur's Justice and Equality Movement (JEM) which is part of a rebel coalition.
"This is an attack deep in Sudanese territory."
JEM and factions of the Sudan Liberation Army from Darfur are grouped in the Sudan Revolutionary Front (SRF) with insurgents from South Kordofan and Blue Nile states.
Sudan Armed Forces (SAF) spokesman Sawarmi Khaled Saad said troops confronted the rebels after they reached Abu Kershola in the far north of South Kordofan.
But rebels then looted Kareem Allaha village before targeting Umm Rawaba town in North Kordofan, Saad said.
"They destroyed the communication tower and electricity station and looted civilian property and a fuel station," he said, quoted by the official SUNA news agency.
"SAF troops in the town responded," Saad said. "Fighting is still going on."
A resident, however, reported no combat in the town but heavy explosions in the surrounding area, where he had seen Antonov bombers and helicopters overhead.
"There are extensive air strikes in the Umm Rawaba area," Bilal said.
Rebel forces had pulled out of the town but remained in the surrounding area where they blocked a highway, he said.
The spokesman for the Sudan People's Liberation Movement-North (SPLM-N), which is based in South Kordofan and Blue Nile states, said the rebel coalition "captured" five areas.
Nur, the other rebel, also said five communities had been attacked.
Umm Rawaba, with a population of several thousand, is about 100 kilometres (60 miles) east of El Obeid, the capital of North Kordofan which produces gum arabica, an ingredient in soft drinks and other products. Sudan is the world's biggest producer of gum arabica.
El Obeid is a major government air base.
Although JEM has occasionally operated just over the Darfur border in the western part of North Kordofan, this is its first strike into the east of the state.
In 2008, JEM pushed all the way to Khartoum's twin city of Omdurman where government forces said the rebels were beaten.
The rebel attack in North Kordofan comes after President Omar al-Bashir on April 1 said the government seeks a broad political dialogue, "including (with) those who are armed."
SRF early this year signed a pact with representatives of opposition political parties to replace Bashir's 24-year regime with a "democratic federal state... based on equality."
Khartoum this week held its first direct talks with the SPLM-N in almost two years. But on Saturday both the government and SPLM-N said talks had stalled over the issue of humanitarian access to the war zone.