U.K. forces warned Iran it was violating international maritime law by seizing the British-flagged oil tanker Stena Impero on Friday.

A dramatic audio recording has emerged of the moments before Iran’s Revolutionary Guard seized a British oil tanker in the Strait of Hormuz on Friday.

The radio exchanges reveal the British navy appearing to warn Iranian forces against seizing the Stena Impero tanker, a move that inflamed tensions amid renewed hostility between Iran and the West.

Meanwhile, a senior official in the government of Oman — which has often played a role as mediator in the region — told NBC News that Iran may have been reacting to the extended detention of one of its ships in the British territory of Gibraltar on Friday.

The recording from maritime security risk firm Dryad Global was obtained by NBC News on Sunday. The U.K.’s Ministry of Defence confirmed its authenticity to NBC News.

“If you obey, you will be safe,” a member of the Iranian navy is heard telling the British-flagged tanker on the radio exchange, while demanding it change course.

A British naval officer aboard the HMS Montrose, according to a call sign referred to in the audio, responds with a warning to Iranian forces.

“Please confirm that you are not intending to violate international law by unlawfully attempting to board,” the British voice says. Read more

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U.K. forces warned Iran it was violating international maritime law by seizing the British-flagged oil tanker Stena Impero on Friday.

U.K. forces warned Iran it was violating international maritime law by seizing the British-flagged oil tanker Stena Impero on Friday.

U.K. forces warned Iran it was violating international maritime law by seizing the British-flagged oil tanker Stena Impero on Friday.