"We remain deeply concerned about Iran's unacceptable actions which represent a clear challenge to international freedom of navigation," a government spokeswoman said.

The government also plans to introduce further measures.

On Friday, the Iranian authorities boarded and seized the Swedish tanker flying the UK flag in Omani waters. The 46,575 cbm ship was then instructed to sail to the Iranian Port of Bandar Abbas.

The British government held a ministerial Cabinet Officer Briefing Rooms meeting on July 20, reaffirming the UK’s desire to deescalate the situation. The officials also discussed how they can guarantee the security of British and international shipping.

Describing the seizure as “totally and utterly unacceptable”, the UK Foreign Secretary Jeremy Hunt said: “The Stena Impero was seized in Omani waters in clear contravention of international law.”

Iran's Islamic Revolutionary Guard Corps said on Friday it had seized the British-flagged Swedish-owned Stena Impero in the Strait of Hormuz for breaking "international maritime rules".

Iranian authorities alleged Saturday the ship had collided with a fishing boat. It said the tanker was now at anchor off the port of Bandar Abbas with all its crew aboard.

Vira Maritime