The rebels said they shot down an army helicopter in revenge for the arrests, a claim denied by the army, which said it had killed 25 rebels.
“We attacked a combat helicopter in clashes at Tabit” in North Darfur, said rebel leader Minni Minnawi.
“Everyone on board was killed,” he told AFP by telephone, without giving a figure.
Government forces swept through the Zamzam camp on the outskirts of the region’s historical capital El-Fasher on Sunday, arresting 37 people and seizing weapons and ammunition.
Zamzam is considered a stronghold of Minnawi’s faction of the Sudan Liberation Army, one of three main rebel groups fighting government troops in Darfur along with the Abdelwahid Nur branch of the SLA, and the Justice and Equality Movement.
“The government attacked the displaced… Our men responded,” Minnawi said.
The army said that it had killed 25 rebels in two days of heavy fighting in Tabit and Jebel Marra, a fertile plateau in the heart of Darfur, adding that the Sudanese air force had “participated actively” in the battles and all its aircraft had returned safely to base.
An army helicopter was forced to land near El-Fasher airport due to a “technical fault” but the crew escaped unharmed, the army statement said.
The death toll could not be independently verified but a spokesman for the SLA-Abdelwahid faction, Ibrahim al-Hilu, confirmed that there had been deadly clashes in Jebel Marra.
The UN-African Union peacekeeping force in Darfur (UNAMID) confirmed heavy fighting in Tabit, which lies around 50 kilometres (30 miles) southeast of El-Fasher, but was unable to confirm that a helicopter had been downed.
“UNAMID confirms reports of intense fighting between the Sudanese armed forces and SLA-Minnawi movement in Tabit,” it said in a statement, adding that the clashes, which began on Monday, were still going on.
Minnawi was the only Darfur rebel leader to sign a peace deal with the Khartoum government in 2006, but he resumed hostilities last month after relations between the two sides soured.
UNAMID said its peacekeepers had been prevented from entering the combat zone by Sudanese army officers who had invoked security concerns.
The peacekeeping mission’s chief, Ibrahim Gambari, urged the two sides to resolve the Darfur conflict through “an inclusive political process, not through the use of force,” the statement said.
UNAMID said that one person was reported to have died following the government’s search operation at Zamzam camp but that the circumstances of his death remained unclear.