London on Saturday advised British ships to avoid the Strait of Hormuz for "an interim period" following Iran's seizure of a British-flagged oil tanker.
"We remain deeply concerned about Iran's unacceptable actions which represent a clear challenge to international freedom of navigation," a government spokeswoman said following an overnight meeting of the government's COBRA emergencies committee.
"We have advised UK shipping to stay out of the area for an interim period."