The UK Ministry of Defence says it captures the vessel Smyrtos in an operation that lasts six hours.

British forces have seized a Russian shadow-fleet oil tanker that was trying to transit the English Channel, Prime Minister Keir Starmer says.

“This successful operation ⁠⁠delivers yet another ⁠⁠blow to Russia and reminds those fuelling ⁠[Russian President Vladimir] Putin’s war in ⁠⁠Ukraine that ⁠⁠we will not let them hide,” Starmer said ‌‌in a post on X on Sunday.

The United Kingdom Ministry of Defence also confirmed the early Sunday seizure of the vessel Smyrtos. It said the tanker, sailing under a Cameroon flag, was boarded by Royal Marine Commandos and National Crime Agency officials with support from Chinook helicopters and other aircraft, a frigate and a minehunter.

“Operations like this require skill, professionalism and courage. I pay tribute to our Armed Forces personnel and all those involved,” Defence Secretary Dan Jarvis said in a statement.

“Russia relies on its shadow fleet to fund its conflict in Ukraine and our interdiction delivers a blow to Putin’s illegal war.”

The operation lasted six hours, the ministry said, adding that the vessel will be “provisionally moved to an anchorage off the South Coast of England and will be monitored for any environmental or safety concerns”.

Last month, the French navy with UK support intercepted an oil tanker suspected of being part of the shadow fleet and falsely sailing under the Cameroonian flag, French authorities said.

In January, French forces impounded another suspected Russian tanker, the Grinch. In March, the Deyna, which sailed from Murmansk under a Mozambican flag, was detained in Marseille.

Oil revenue is a key part of Russia’s economy and helps offset the cost of the more than four-year war on Ukraine.

Russia is believed to be using a fleet of hundreds of ships to evade international sanctions imposed because of the war. The UK and other countries have pledged to crack down on the sanctions-busting “shadow fleet”.

According to the UK Ministry of Defence, Britain has imposed sanctions on more than 500 vessels to date, and the measures are having an impact with Russia’s oil and gas revenues declining by 24 percent in 2025 compared with the previous year.

Several Western countries have imposed sanctions on Russian vessels over its 2022 full-scale invasion of Ukraine.

Putin has condemned the capture of Russia-linked vessels as “piracy”.