TEHERAN (AFP) - At least nine people were injured in a blast on Sunday (May 23) at a plant producing explosive materials in Iran's central province of Isfahan, ISNA news agency reported.

The blast ocurred at Sepahan Nargostar Chemical Industries at 4am local time (2330 GMT) due to "unclear reasons still being investigated", said Mr Mansour Shisheforoush, head of the province's crisis management organisation.

Nine factory workers were injured and transferred to the hospital, he added.

He said several investigative teams are currently at the scene to determine the cause of the blast.

The plant is located about 45km north-west of Isfahan city.

The company manufactures "industrial-commercial explosive materials" and was established in 1941, according to its website.