Sudan's President Omar al-Bashir, giving a rare battlefield toll, says 163 members of the controversial Rapid Support Forces have been killed in Darfur and South Kordofan.

Bashir "referred to the martyrdom of 163 of the troops and the wounding of others in the operations during five months," according to comments carried late Sunday by the official SUNA news agency.

In an April report, UN chief Ban Ki-moon said Rapid Support elements had attacked and burned villages in Darfur, where Khartoum said they were deployed against rebels.

After Sudanese opposition leader Sadiq al-Mahdi reportedly made similar accusations, state security agents detained him for about a month.

Rapid Support, which is under the authority of the National Intelligence and Security Service (NISS), has denied that their unit raped, looted or committed arson.

Violence throughout Darfur reached its worst levels in a decade this year, displacing about 300,000 people from late February to mid-April before unrest began to ease.

Mohamed Ibn Chambas, head of the UNAMID peacekeeping mission in Darfur, has said that activities of the RSF were of "particular concern".

But rebel offensives, criminal activity and inter-communal fighting also contributed to this year's "alarming escalation of violence", he said.

Fatou Bensouda, chief prosecutor for the International Criminal Court (ICC), has called Rapid Support Forces a new version of the Janjaweed militia.

Insurgents from black tribes in Darfur rose up 11 years ago against what they said was the domination of Sudan's power and wealth by Arab elites.

In response, the government turned to Janjaweed militia recruited from Arab tribes, and who have since been incorporated into official paramilitary units.

Rapid Support troops have also been deployed against a three-year rebellion in South Kordofan state.

Bashir, who is wanted by the ICC for alleged war crimes in Darfur, said Sudan "will be free from rebellion" by year-end. The government has made similar vows before.