Putin's shadow fleet sailors may be able to claim asylum if Britain seizes their ships in the English Channel, ministers have warned.

Foreign Secretary Yvette Cooper and Home Secretary Shabana Mahmood are understood to have raised concerns to this effect, according to The Telegraph.

It is feared apprehending the Russian tankers could allow sailors brought ashore by British forces to make use of the UK asylum system, according to Whitehall sources. 

Many of the seamen onboard are mercenaries hired by the Kremlin who could argue they were at risk of persecution if they returned to Russia or their home country.

Foreign nationals arriving in Britain are eligible to claim asylum if they are at risk of persecution, including because of the 'political situation' where they come from. 

These rules also apply to small boat migrants, who are often rescued by the RNLI or Border Force in the Channel and brought ashore to have asylum claims processed. 

If the shadow fleet sailors had their claims rejected, they could appeal the decision under the European Convention on Human Rights (ECHR), which can take years. 

It is thought Russia may have placed spies on the tankers in hopes the vessels will be intercepted and the agents brought onto UK shores. 

Prime Minister Sir Keir Starmer has faced increasing pressure in recent days to tackle sanctioned Russian naval traffic passing through British waters. 

He promised last month to 'go after' the ships, insisting special forces and officers from the National Crime Agency would board and impound the vessels. 

But despite his assurances, it has been revealed this week a shadow fleet tanker was able to travel through the Channel, escorted by a Russian frigate. 

Three more sanctioned tankers then sailed through the British waterway the following day. 

The Royal Navy has not yet seized any ships, on the legal advice of the Attorney General, Lord Hermer, who warned it could breach international human rights law. 

Conservative leader Kemi Badenoch said: 'A legal system, defended by our lawyer-in-chief Keir Starmer, that allows asylum claims from Russian mercenaries is simply not fit for purpose.

'We need to put our national interest first and that means leaving the ECHR, because we know, having tried everything else, that nothing else will work to make our borders stronger.' 

Ms Cooper and Ms Mahmood are understood to be working on a solution to the legal loophole to allow the navy to seize ships without letting crews remain in Britain. 

They first raised concerns in January, when the US seized Russian tanker Bella 1 in UK waters. 

American authorities arrested the captain and first mate - but 26 other sailors were briefly sent to an army reserve centre in Inverness.

The men, variously from Russia, Ukraine, Chile and Bulgaria, were processed by Border Face at the base before being flown out of the UK. 

But officials and government lawyers are concerned any similar arrivals could find a way to legally remain in Britain under immigration laws. 

The US faced claims the capture was illegal - but the White House insisted the seizure was legitimate. No legal action has been brought over the incident. 

British authorities are also understood to be examining how France has dealt with the issue when apprehending tankers in the Mediterranean. 

Government insiders said the Ministry of Defence would need to meet a high legal threshold to be able to start a raid in the Channel. 

Without this, officials would likely face legal action at an international maritime tribunal. 

Opponents have claimed Labour has been too slow to act, allowing Russian president Vladimir Putin to transport oil and gas for selling to allies including China and Iran. 

Defence Secretary John Healey confessed on Thursday there was 'more we can do' to stop the shadow fleet. 

But he said the Kremlin's decision to escort tankers with warships showed Britain had successfully diverted Russian resources away from the war in Ukraine. 

A Ministry of Defence spokesman said: 'We will not comment on specific operational planning or give a running commentary as this could compromise our ability to successfully take action against these ships, only benefitting our adversaries.

'In general terms, any target ship will be individually considered by law enforcement, military and energy market specialists before an operation is executed.'

It comes after the Russian frigate Admiral Grigorovich was seen accompanying two 'shadow fleet' vessels past Britain's south coast on Wednesday. 

The 'senior service' was only able to rustle up a support ship to watch them head for the Black Sea.

Last month, Sir Keir gave approval for Britain's commandos to board and halt shadow fleet vessels as they pass through UK waters. 

The move came as part of his commitment to pursuing the sanction-breaking ships 'even harder'.

But according to The Telegraph, RFA Tideforce, an auxiliary tanker armed with only light defensive weapons, simply followed the flotilla past Dover without intervening.

It came as the prime minister was branded 'all mouth and no trousers' on defence by Tory leader Mrs Badenoch.

She accused the PM, who went on a tour of the Gulf this week, of posturing on the world stage over the Middle East war while failing to rearm Britain.

Fears have been raised in recent weeks about the state of the Navy, after Iran hit an RAF base in Cyprus in retaliatory strikes following attacks by the US and Israel. 

Officials were only able to rustle up a single ship to send to the Mediterranean to protect the country - and it arrived three weeks late.

Mrs Badenoch said: 'At a time of war in Europe and war in the Middle East, at a time when those conflicts are affecting every family across Britain, at a time when Britain's place in the world is in flux, our Government literally doesn't have a plan.'