Khartoum - Heavy fighting erupted in El Fasher on Tuesday, residents said, breaking an uneasy calm in the second most populous city of Sudan's restive Darfur region.
"They are fighting inside El Fasher town - heavy fighting," one resident told AFP by telephone, adding that he could not identify the combatants, although some were in uniform.
Continuous gunfire was audible over the phone line as he spoke.
A second person in El Fasher, the capital of North Darfur state, said the shooting started at about 04:00 in the east of the town, and was continuing.
"I heard the sound of heavy weapons," the resident said.
"I am in my house and I'm not going out to work."
Fighting had also been reported in El Fasher on Monday.
In early April, El Fasher residents told an AFP correspondent that the town had been gripped with fear for a month, since government-linked paramilitaries arrived.
"Shooting for no reason"
They said the hard-faced men were "shooting for no reason" and had a strong presence in El Fasher's east side.
Residents claimed some were from the Rapid Support Forces, a counter-insurgency unit that the head of the Unamid peacekeeping mission in Darfur said had "perpetrated attacks on communities" as violence rose to alarming levels earlier this year.
Commanders of the RSF last week denied such allegations and said the unit was "on holiday" after completing its Darfur mission.
Similar government-linked units and militias remain in Darfur, but Khartoum has faced mounting economic problems since South Sudan broke away in 2011 and has had difficulty controlling them.
Rebel-government battles are no longer the main source of violence in Darfur, where insurgents from ethnic minority groups launched an uprising against the country's Arab elites in 2003.
The deteriorating economy has led to worsening crime and escalating tribal clashes, a February report by UN chief Ban Ki-moon said.