Roman Abramovich: Chelsea owner and close friend of Putin must reveal finances to get back into the UK

The Kremlin has accused the UK of acting in an 'unprincipled and unfriendly' way amid deteriorating relations

Chelsea FC owner Roman Abramovich will be forced to open up his books to prove his vast UK-held wealth is legitimate if he wants to return to Britain.

The billionaire and close friend of Vladimir Putin has been caught in a clampdown on oligarchs after his visa ran out, amid rising tensions following the poisoning of Russian former spy Sergei Skripal.

Mr Abramovich and some 700 other super-rich Russians who still hold visas must show their money has nothing to do with crime, criminals or anyone whose actions are not “conducive to the public good”.

Moscow lashed out on Monday, accusing the British government of stoking anti-Russian hysteria and of acting in an “unfriendly and unprincipled” way.

But after reports emerged that Mr Abramovich’s visa had elapsed, Downing Street insisted that all new applications for rich investors would be subject to stricter rules implemented in 2015.

Theresa May’s spokesman said the government could not comment on individual cases, but added that it is a “logical conclusion” that someone who qualified under the old system may not under the new one.

Downing Street also said that 700 Russians whose “tier 1” investor visas are yet to elapse will be looked at again under a review launched by former home secretary Amber Rudd.

Asked if the Home Office would look at individual cases, Ms May’s spokesman said: “The answer to that is yes.

“We are looking at visas which were issued pre-April 2015, which is when the rules were toughened ... in relation to people who are still in that investor visa route. That could be people who made initial and extension applications within the years covered by the review.

“The work on that review is ongoing.”

But it is the focus on Mr Abramovich that is likely to particularly raise hackles in Moscow, given his close relationship to Mr Putin.

Under the new visa system, officials could refuse Mr Abramovich a visa if there are mere “reasonable grounds to believe the applicant is not in control of [UK-held funds], funds were obtained unlawfully or by conduct which would be unlawful in the UK, or the character, conduct and associations of a third party providing the funds in granting is not conducive to the public good”.

The billionaire is one of only a few oligarchs to have successfully transitioned from Boris Yeltsin’s rule to Mr Putin’s, with the pair even talked about as having a “father and son” relationship.

He was able to amass his fortune after he and another businessman with close ties to the Kremlin, Boris Berezovsky, were able to buy Siberian oil giant Sibneft for less than £148m, selling it later at a huge profit.

While Mr Berezovsky has since died, Mr Abramovich’s estimated worth is between £8.3bn and £9.3bn, with substantial assets believed to be UK held, including Chelsea Football Club, worth some £1.4bn.

The Independent understands it is likely that the businessman will be forced to provide information on his broader fortune, in order to satisfy enquiries about his UK-held wealth.

According to Forbes, Mr Abramovich owns the world’s second-largest yacht, 533ft Eclipse, bought for close to £300m in 2010.

He sold his 73 per cent stake in Sibneft to state-owned gas titan Gazprom for £9.7bn in 2005, and has spent some £1.9bn in the Chukotka region, where he worked as governor and chairman of the local duma from 2001 to 2013.

Other rules under the new visa system mean investment funds used to qualify for the visa cannot be sourced by a loan and must be invested in “permitted” assets – which do not include property or moveable assets like art or antiques.

Kremlin spokesman Dimitry Peskov said: “All I can say is that our businesses are often battling unfriendly and unprincipled behaviour.

“Investors in other countries will see what is happening in the United Kingdom. I would suggest that as far as investor attractiveness is concerned, this is a step backwards for UK.”

The Home Office said it would examine its approach to the “tier 1” investor visa route following the March nerve agent attack on Mr Skripal and his daughter Yulia in Salisbury.

The ex-spy was released from hospital last week, more than 10 weeks after the poisoning which Ms May has blamed on Russia.

On Monday, the UK’s broadcasting watchdog also opened three new investigations into Kremlin-backed TV channel RT, over claims of bias in its news coverage.

It brings the total number of open investigations into RT, formerly Russia Today, from eight to 11, with Ofcom saying the further investigations will look at “the due impartiality of news and current affairs programmes broadcast” on the channel.