Iran said it had seized a British oil tanker in the Strait of Hormuz on Friday but denied Washington's assertion that the U.S. Navy had downed an Iranian drone nearby this week, as tensions in the Gulf region rose again.

Britain said it was urgently seeking information about the Stena Impero tanker, which had been heading to a port in Saudi Arabia and suddenly changed course after passing through the strait at the mouth of the Gulf.

The tanker's operator, Stena Bulk, said in a statement the ship was no longer under the crew's control and could not be contacted.