The US Coast Guard stopped the tanker which was being shadowed by a Russian submarine on Wednesday, after pursuing it for more than two weeks across the Atlantic as part of Washington's efforts to blockVenezuelanoil exports.

Britainsaid its armed forces gave "pre-planned operational support, including basing" following a US request for assistance.

It said a military vessel provided support for the US forces pursuing the tanker, and the Royal Air Force providedsurveillancesupport from the air.

In a post on X, the US military's European Command thanked the MoD for its "unwavering support" during the operation.

Trump orders blockade of 'sanctioned' Venezuela oil tankers

Crackdown on 'sanctions busting'

The Marinera, a Venezuelan-linked tanker formerly known as the Bella-1, was not carrying any oil.

But the ship is alleged to be part of the shadow or "ghost" fleets used by Russia, Iran and Venezuela to avoid western sanctions.

Britain's DefenceSecretary John Healey said theoperation targeted a vessel "with a nefarious history" linked to Russian and Iraniansanctionsevasion networks.

This action formed part of global efforts to crack down on sanctions busting, he said in a statement.

He said Britain's support was provided "in full compliance with international law", adding that the UK "will not stand by as malign activity increases on the high seas".

He added that theUnited Stateswas Britain's closest defence and security partner: "The depth of our defence relationship with the US is an essential part of our security, and today's seamlessly executed operation shows just how well this works in practice."

France investigates Russian shadow fleet tanker anchored off coast

The Marinera has been under sanctions from the US treasurysince June 2024.

The US accuses it of carrying illicit cargo for the Iranian-backed Lebanese militant groupHezbollah.

(with newswires)

Originally published on RFI