At least 17 suspected ‘zombie tankers’ a day are thought to be passing through the Channel between the South Hams and Brittany.

The figures come from the national publication ‘The i Paper’ who believe the increase in vessels from Russia’s shadow fleet is due to an increase in sea ice which has closed the country’s Arctic coast.

The ships are often carrying sanctioned Russian oil which is sold to provide a colossal income for Russia to continue it’s war against Ukraine.

They can also be used for other illicit trade and operations against the west such as dragging their anchors and damaging undersea cables.

The fleet is thought to be at least 1,400 and many countries including UK are imposing sanctions.

Under the United Nations Convention on the Law of the Sea (UNCLOS), ships of all states, even if sanctioned are to be given the right of ‘innocent passage through international waters.

They may not change their flag mid-voyage as was the case of a Russian tanker the Mariniera seized earlier this month in Icelandic waters by the US with help from the UK.

Suspected criminality could provide grounds for boarding a ship.

The Ministry of Defence says: ‘deterring, disrupting and degrading’ the Russian shadow fleet is a priority but in practice it may be difficult to do without the backing of the US.

To board just one of the daily 17 or so vessels would require a Special Forces squadron, at least two surveillance aircraft, a re fuelling tanker and specialist helicopters.

From a legal standpoint the UK has blacklisted 549 tankers, the EU 580 and the US 744 but the overlap between them is just 195 but for the vessels to be legally stopped there needs to be unification of the sanction lists.

The rules around shipping are also immensely complicated and full of loopholes.

The UK has a 12 nautical mile territorial limit but also a far larger Exclusive Economic Zone (EEZ) first agreed in 1977 which stretches 200 miles and within which it has sovereign rights for exploiting natural resources like fish,oil and gas.

In the English Channel where the coast of England and France are less than 400 nautical miles apart, a median line is used to mark the boundary.

Under UN law the UK could board a vessel passing close to its waters if there was a reasonable suspicion that it was sailing under a false flag.

This right would be strengthened if the ship were within British territorial waters.

Russian ships are banned from entering UK ports and if they attempted for example to sail to Plymouth may be given a detention, port entry or movement direction under the terms of the sanctions.

There are fears many of the vessels in Russia’s shadow fleet may be in a poor condition which could cause environmental and safety problems.

Many are sailing under false flags, masking their identities.

Defence Secretary John Healey speaking in October told President Putin: “If Nato is threatened, we will act.”