Fire raged and explosions tore through the night sky early Wednesday at the Yarmouk military factory in the Sudanese capital Khartoum, witnesses and state-linked media said.

"The authorities are controlling a fire in the El Yarmouk military manufacturing facility," the Sudanese Media Centre, which is close to the security apparatus, said in a brief alert.

"It is a military factory," said one witness in the southern Khartoum neighbourhood who heard "big, big explosions."

Several kilometres from the scene an AFP reporter could see two or three fires flaring across a wide area, with heavy smoke and intermittent flashes of white light bursting above.

"I hear explosions, and now a fire truck has gone inside and soldiers are guarding the area," another area resident said.

Abdul Rahman Al-Khider, the governor of Khartoum state, told official media that an explosion occurred at midnight Tuesday, followed by a fire.

"Preliminary investigation says the explosion happened in a store room," he said, dismissing speculation that the blaze had been caused by "other reasons."

Khider said some people were hospitalised because of smoke inhalation but he gave no numbers.

The fires appeared to be extinguished by 0030 GMT, more than three hours after they began, an AFP reporter said.

A September report from the Small Arms Survey, a Swiss-based independent research project, said evidence from weapons packaging suggests that Chinese-origin weapons and ammunition are exported to the state-owned Yarmouk Industrial Complex.

From there they have subsequently moved into Sudan's far-west Darfur region which has been plagued by conflict for almost a decade, the report said.

Small Arms Survey said it was not clear whether Yarmouk served simply as a recipient "or whether they repackage or even assemble the Chinese-made weapons."

In 1998 Human Rights Watch said that a coalition of Sudanese opposition groups had alleged that Sudan stored chemical weapons for Iraq at the Yarmouk facility but government officials strenuously denied the charges.