The Iranian flag has been hoisted over a seized British oil tanker in footage broadcast on the country's state TV.
Stena Impero was seized by Iran's Revolutionary Guards in the Strait of Hormuz on Friday, sparking a major diplomatic crisis.
The clip appears to have been recorded in the southern port of Bandar Abbas, the Daily Mail reported.
Footage also seems to show Iranian armed forces patrolling the deck of the UK-flagged ship after it was taken.
Earlier today a recording revealed the tense exchange between the Royal Navy and Iranian military in the run-up to the incident.
In the clip, an Iranian vessel can be heard repeatedly warning the British-flagged Stena Impero to change course, saying: "If you obey you will be safe."
HMS Montrose tells the Stena Impero: 'As you are conducting transit passage in a recognised international strait, under international law your passage must not be impaired, impeded, obstructed or hampered.'
In response, the Iranian patrol vessel tells HMS Montrose: 'No challenge is intended.... I want to inspect the ship for security reasons.'
British Foreign Secretary Jeremy Hunt said Iran's action "raises very serious questions about the security of British shipping and indeed international shipping in the Strait of Hormuz."
Mr Hunt added the vessel was seized in Omani waters in "clear contravention of international law".
The ship was carrying no cargo and its crew are said to be safe and in good health.
While the Impero is British-flagged it is Swedish-owned and it is not thought any of the 23 crew members are British.
However the presence of the flag is symbolic and politically and historically means the UK has responsibility for ensuring the vessel is safe.
It's feared a continuing escalation will cause issues for the oil industry — a third of the world's oil is shipped through the relatively narrow Strait making it something of a bottle neck.
