The measures were agreed upon by Poland, Germany, Britain, the Netherlands, the five Nordic nations and the three Baltic states, said Estonia, where leaders of the 10-nation Joint Expeditionary Force were due to meet on Tuesday, Reuters reported.

Western nations have slapped sanctions on a wide range of ships they say are used by Moscow to avoid restrictions on the export of Russian oil and other cargoes.

Vessels in the shadow fleet are not regulated or insured by conventional Western providers.

“We are taking concerted steps to deter Russia's shadow fleet and avoid attempts to evade sanctions,” Estonian Prime Minister Kristen Michal said in a statement.

Denmark, Sweden, Poland, Finland and Estonia will begin to check insurance documents of ships under suspicion passing through the English Channel, Danish straits, the Gulf of Finland and the sound between Sweden and Denmark, he added.