Riyadh: A fire which broke out at Saudi Arabia's biggest prison left 67 inmates dead as well as about 20 badly burned, a security source said, quoting a provisional toll.

"The fire is still burning and the rescue operation still going on," an official said asking not to be named.

The prison service earlier announced "a certain number" of prisoners had died in the blaze.

"A fire started Monday afternoon at a detention centre in Riyadh causing a certain number of deaths among the prisoners," the director-general of the service told the official Saudi Press Agency, which did not provide his name.

Firemen and emergency workers "intervened immediately", the director-general said, adding that Interior Minister Prince Nayef bin Abdul Aziz had ordered an inquiry into the "causes and consequences" of the fire.

The prison service chief said the number of deaths and the results of the inquiry would be announced at a later date.

Agencies