Moscow said it fired warning shots at the Palau-flagged Sukru Okan after it failed to respond to a demand for it to halt on Sunday.

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In the video, which appears to be bodycam footage, the Russian servicemen move down a corridor carrying automatic weapons and enter the vessel's bridge as they question the captain why the ship had not stopped.

"Stop machine, stop machine," one of the armed Russians says as crew members first have their hands on their heads and then kneel as a Russian military helicopter approaches.

"Keep calm and listen to me," another Russian says. "Good day sir. I am Russian naval officer - please don't shoot my group on video."

It appears the vessel's failure to stop may have been caused by a language barrier.

In one clip released by the defence ministry, a Russian demands: "Speak English."

"Yes, I am speaking English," a crew member replies.

The Russian officer then questions the captain - through a crew translator - about why the ship did not stop when it was asked to.

The captain had misunderstood the Russian demand to stop, the translating crew member says.

"You, bad understand," the crew member says in English.

"Thank you, you good day sir," the Russian officer says as he leaves.

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The work of the inspection team was carried out "professionally in accordance with the requirements of international documents", Russia's defence ministry said.

"After the completion of the work of the inspection team on board the Sukru Okan, a verification protocol was drawn up, (and) the ship continued to move to the port of Izmail (southwestern Ukraine)," it added.