UK prime minister Theresa May will chair a meeting of the government's emergency committee Cobra on Monday as the country considers its response to the seizure of a British-flagged tanker by Iran in Friday.
The 50,000-dwt Stena Impero (built 2018) was intercepted in the Middle East Gulf in retaliation for the seizure of a VLCC carrying Iranian oil in Gibraltar earlier this month.
May will discuss the security of shipping in the region, Sky News reported.
Foreign secretary Jeremy Hunt will also update the UK parliament on the situation, with ministers reportedly considering freezing Iranian regime assets.
New audio
On Sunday, new audio was released by maritime security risk firm Dryad Global of the Iranian Revolutionary Guard and the UK navy giving instructions to the Stena Bulk tanker before it was seized.
An Iranian officer is heard saying: "If you obey, you will be safe. Alter your course to 360 degrees immediately, over."
The British frigate HMS Montrose then tells Stena Impero: "I reiterate, that as you are conducting transit passage in a recognised international strait, under international law your passage must not be impaired, impeded, obstructed or hampered.
"Please confirm you are conducting transit passage in a recognised international strait."
The vessel later asks the Iranians to "please confirm that you are not intending to violate international law by unlawfully attempting to board the MV Stena."
The Iranians then repeat their request for the tanker to turn around.
The ship has been taken to Bandar Abbas in Iran.
