Two oil tankers under US sanctions are sailing east through the English channel towards Russia, prompting speculation over whether the US and UK would be willing to seize further vessels linked to Moscow.

The Aria and the Tia, which has changed its name and country of registration several times, were both travelling south of Britain a day after the Marinera oil tanker was captured in the Atlantic by the US with UK help.

John Healey, the defence secretary, told MPs on Wednesday evening that the seizure of the Marinera was justified not only because it was falsely flagged but it was also part of Russia’s shadow fleet that ships oil illicitly “to bankroll its illegal invasion of Ukraine”.

That created an expectation that the UK, perhaps with the help of the US, would be willing to target other Russian or Russia-linked tankers near the country that have already been sanctioned by the US Treasury.

On Thursday, the Ministry of Defence, when asked if it was aware of the sanctioned ships, said that it would not discuss on any possible plans to seize the vessels or “give a running commentary on live maritime traffic websites”.

But a spokesperson returned to Healey’s comments from the night before: “The defence secretary set out in parliament yesterday that deterring, disrupting and degrading the Russian shadow fleet is a priority for this government.”

The Tia, using the name Tiavan, is on a voyage from Turkey to a port on Russia’s Gulf of Finland, due to arrive on 13 January, according to Lloyd’s List. Under the name Tia it was sanctioned by the US for carrying crude oil from Venezuela in 2024, after which its name was changed to Arcusat and finally Tiavan.

The Aria is registered under the flag of Barbados, and was recorded sailing between Plymouth and Jersey early on Thursday evening, heading towards the Ust-Luga commercial port in the eastern Baltic. It is listed as sanctioned by the US Treasury, with a note that it is linked to Russia’s largest shipping company.

On Wednesday afternoon, US forces seized the Marinera oil tanker, previously the Bella 1, north-west of the British Isles in an operation supported by the British navy and air force, after following it for two and a half weeks from the Caribbean.

It had been sailing towards Venezuela, but the crew had refused to give permission for the US Coast Guard to board as it approached the South American country. The boat then fled north up the Atlantic, changing its name and adopting a Russian registration, though this was not enough to put off the US military.