Tehran: Iran said on Sunday that the speed of its investigation into a British-flagged tanker depends on the cooperation of its crew, after ignoring calls to hand back the vessel.

The Stena Impero tanker was impounded with its 23 crew members on board at the port of Bandar Abbas after the Islamic Revolutionary Guard Corps seized it on Friday. Its crew is made up of 18 Indians, including the captain, three Russians, a Latvian and a Filipino.