The vessel, Jaguar, which Britain added to its sanctions list last Friday, is one of about 100 in Russia’s “shadow fleet”, a term western countries use for ships they accuse Moscow of deploying to avoid international sanctions.

They are typically not regulated or insured by conventional western organisations.

The ship was near Naissaar Island, off Tallinn, when the Estonian navy communicated with it by radio at 3.30pm on Tuesday, commander Ivo Vark told Reuters in an email message.

As it was sailing “without a nationality”, Estonia “had an obligation to verify the vessel’s documents and legal status”, Vark said yesterday.

“The vessel denied cooperation and continued its journey towards Russia… given the vessel’s lack of nationality, the use of force, including boarding the vessel, was deemed unnecessary.”

An Estonian patrol escorted the Jaguar until it reached Russian waters, Vark added.

On X, Estonia’s foreign minister said Russia “must face tougher, faster sanctions” in response.

“With the info op that followed, Russia has clearly tied itself to the shadow fleet,” Margus Tsahkna posted.

The Estonian defence ministry declined to comment.

Today, the Jaguar was anchored near the Russian port of Primorsk, Marine Traffic data showed.

It was listed there under the flag of the central African nation of Gabon.

Vark was responding to a Reuters request for comment on a recording on X purporting to show the boarding attempt, but which could not be independently verified.

Filmed from a bridge of a tanker whose IMO identification number matches that of the Jaguar, the video shows a navy patrol boat, a helicopter and a patrol aircraft hovering nearby.

“This is Estonian warship… follow my instructions, alter your course to 105 immediately,” says a voice on the radio.

In Russian, a voice says off-camera, “We are met by helicopters, they demand we go on anchor.”

A military jet, which Estonia does not operate, is also glimpsed flying nearby.

Vark did not reply to a query if the incident was connected to Tuesday’s alleged breach of Estonian airspace by a Russian Su-35 military jet that drew a protest from Estonia.

On X, Margarita Simonyan, head of Russia’s state media outlet RT, who posted the video, said the jet was a Russian Su-35, sent to prevent the vessel’s seizure.

In an incident on April 11, Estonia detained and boarded a Russia-bound oil tanker, Kiwala, accusing it of sailing without a valid country flag.

The tanker cooperated, and was released two weeks later.