An audio recording released by a maritime security firm reveals how an Iranian naval officer threatened the crew of a British-flagged vessel through the Strait of Hormuz just before it was seized.

In the recording, an officer of Iran’s Islamic revolutionary guard is heard telling the Stena Impero to change course, adding: “You obey, you will be safe.”

The audio released Sunday by Dryad Global shows how the British Navy was unable to prevent the ship's seizure by Iranian forces on Friday.

The British officer is heard saying that the transit of the vessel must not be impaired under international law.

Iran’s Guard seized the Stena Impero and another British oil tanker in the Strait of Hormuz on Friday over what it claimed were violations of international regulations.

Tensions high as Trump approves new Iran sanctions: In pictures Show all 17 1 /17 Tensions high as Trump approves new Iran sanctions: In pictures Tensions high as Trump approves new Iran sanctions: In pictures Iran claims that in this picture released by Iran state TV, their surface-to-air missile is seen as it shoots down a US surveillance drone EPA Tensions high as Trump approves new Iran sanctions: In pictures This photo shows US RQ-4A Global Hawk unmanned surveillance drone. A drone of this model was shot down by Iran on Thursday 21 June AFP/Getty Tensions high as Trump approves new Iran sanctions: In pictures An oil tanker is on fire after it was subject to a suspected attacked at the Gulf of Oman on June 13. The US has blamed Iran for the attack Reuters Tensions high as Trump approves new Iran sanctions: In pictures Iran claims that in this picture released by Iran state TV, debris from the downed US drone is seen after it was recovered from Iranian waters AFP/Getty Tensions high as Trump approves new Iran sanctions: In pictures Smoke billows from an oil tanker after it was subject to a suspected attacked at the Gulf of Oman on June 13 Reuters Tensions high as Trump approves new Iran sanctions: In pictures US President Trump holds up a signed executive order to increase sanctions on Iran on 24 June AP Tensions high as Trump approves new Iran sanctions: In pictures Iranian President Rouhani stated in a televised address that the White House is "afflicted by mental retardation" following the increase in sanctions on 25 June EPA Tensions high as Trump approves new Iran sanctions: In pictures An Iranian navy boat tackles the fire on the Norwegian owned Front Altair oil tanker after it was hit in a suspected attack AFP/Getty Tensions high as Trump approves new Iran sanctions: In pictures Iran claims that in this picture released by Iran state TV, debris from the downed US drone is seen after it was recovered from Iranian waters AFP/Getty Tensions high as Trump approves new Iran sanctions: In pictures Smoke billows from an oil tanker after it was subject to a suspected attacked at the Gulf of Oman on June 13 Reuters Tensions high as Trump approves new Iran sanctions: In pictures A screenshot from a video released by the US Department of Defense that the US claims to show Iranian removing an unexploded limpet mine form the hull of the Japan-owned ship that was attacked in the Gulf of Oman on June 13 Getty Tensions high as Trump approves new Iran sanctions: In pictures An item reportedly found on the Japan-owned oil tanker that was attacked on June 13 in the Gulf of Oman AFP/Getty Tensions high as Trump approves new Iran sanctions: In pictures A handout photograph from the US Department of Defense shows a composite material that the US claim was left behind on the hull of the Japan-owned oil tanker following the removal of an unexploded limpet mine Getty Tensions high as Trump approves new Iran sanctions: In pictures A view from the cabin of an Iranian navy boat as it tackles the fire on the Norwegian owned Front Altair oil tanker after it was hit in a suspected attack EPA Tensions high as Trump approves new Iran sanctions: In pictures Release by US government A picture released by U.S. Central Command shows damage to the hull of the oil tanker Kokuka Courageous. The picture suggests that the ship is 'likely' to have been hit by a mine as the US Secretary of State Mike Pompeo moves to blame Iran for the suspected attack Reuters Tensions high as Trump approves new Iran sanctions: In pictures Smoke billows from an oil tanker after it was subject to a suspected attacked at the Gulf of Oman on June 13 Reuters Tensions high as Trump approves new Iran sanctions: In pictures Release by US government A picture released by U.S. Central Command shows damage to the hull of the oil tanker Kokuka Courageous. The pictures suggests that the ship is 'likely' to have been hit by a mine as the US Secretary of State Mike Pompeo moves to blame Iran for the suspected attack EPA

The incident happened at around 4pm UK time. The Stena Impero, “was approached by unidentified small crafts and a helicopter during transit of the Strait, while the vessel was in international waters”, according to the tanker’s owners, Stena Bulk.

Britain has called Iran’s capture of the Stena Impero in the Strait of Hormuz on Friday a “hostile act”.

The port authority chief was quoted by the semi-official Tasmin news agency, as saying that it was “causing problems”.

But the incident comes after tensions between the US, the UK and Iran flared up, and Iranian officials say the move came in response to Britain’s role in seizing an Iranian supertanker loaded with some 2 million barrels of crude oil weeks earlier.

Earlier in July, Royal Marines seized an Iranian tanker which was suspected of breaking European Union sanctions off the coast of Gibraltar.

Foreign secretary Jeremy Hunt said it would be released if Tehran guaranteed its oil would not be given to Bashar al-Assad’s regime in Syria.

Days later, Iranian boats tried to impede a British oil tanker before being seen off by a Royal Navy frigate in the Strait of Hormuz.

Britain sent a second warship, HMS Duncan, to the Persian Gulf after the incident.

The escalation of tension comes after Donald Trump unilaterally withdrew the US from a 2015 deal, which saw Iran curtail its nuclear programme in exchange for normalised economic relations, and tightened restrictions on trade with Iran.

Other world powers have tried to salvage the deal, but Iran has begun a new uranium enrichment programme in response to the lack of economic benefits.

Agencies contributed to this report.