Authorities said later no one was killed and the blaze was under control.

The fire sent a cloud of grey and orange smoke over the city and a Reuters witness saw at least four buildings burning in a large open plot in el-Shagara, south of the city centre.

Western diplomats said they had received reports the fire was started accidentally when a vehicle was refuelled.

Sudan's interior ministry in a statement said the blaze was under control. It did not mention the cause of the fire or name the company that owned the damaged buildings.

The statement said no one was injured in the fire which it said broke out in a "strategic" area, near oil storage blocks.

Oil last year generated more than 60 percent of Sudan's export revenues and helped fuel growth despite U.S. sanctions.