A prominent Sudanese human rights group has accused the country's army and security forces of torturing people to death and operating "execution chambers".

The Emergency Lawyers group said it had documented hundreds of arrests in the capital Khartoum. It said that in the "worst cases", some captives had later been found dead with evidence of torture, BBC reported.

The Sudanese army recaptured the city from the paramilitary Rapid Support Forces (RSF) in March, against which it is fighting a bitter civil war that has killed tens of thousands in two years.

The army did not respond to the BBC's request for comment on Sunday.