The British operator of an oil tanker seized by armed guards in the Gulf said the vessel, the Stena Impero, was in full compliance with all navigation and international regulations.
The tanker was boarded by armed guards earlier on Friday. Iran's state news agency IRNA quoted a military source as saying the vessel had turned off its tracker, ignored warnings from the Revolutionary Guards and was sailing in the wrong direction in a shipping lane.
"There are 23 seafarers onboard of Indian, Russian, Latvian and Filipino nationality," said Erik Hanell, President and Chief Executive of the operator, Stena Bulk.
"There have been no reported injuries and the safety and welfare of our crew remains our primary focus."