"The tanker had turned off its tracker and ignored several warnings by the Guards before being captured," an unnamed military source told IRNA.
The same source told IRNA that the tanker's violations also included sailing in the wrong direction in a shipping lane and ignoring directives.
Britain said it was urgently seeking information about the Stena Impero after the tanker, which had been heading to a port in Saudi Arabia, suddenly changed course after passing through the Strait of Hormuz at the mouth of the Gulf.