A container vessel of unknown ownership has capsized and sunk in an Iranian port.

The Tanzania-flagged, 2,100-gt Anil (built 1989) turned over on Tuesday at a jetty in the southern terminal of Assaluyeh, the state-controlled IRNA news agency reported.

The report said the ship capsized because boxes on board were configured incorrectly at dock No. 9.

Photos showed a number of containers floating in the water at the dock, with the vessel submerged on its side, although one photo from the AP news agency showed the hull bottom facing upwards.