Roman Abramovich, the owner of Chelsea Football Club, could be asked to explain the source of his vast wealth before he is granted a new UK visa.
The Russian oligarch’s investor visa application is still being considered after his previous one, which was granted before tighter regulations were introduced in April 2015, expired.
No 10 said that while it would not comment on individual cases, it was the “logical conclusion” that some wealthy individuals who had applied under the investment visa route before the changes would no longer be eligible.
The government launched a further crackdown on wealthy investors coming to the UK after the Salisbury poisoning, increasing tensions between Britain and Russia.
Downing Street confirmed it was looking at individuals who were still in the UK and holding tier 1 visas, which allow anyone who invests more than £2m in the British economy to stay for 40 months.
Responding to the reports on the delay with Abramovich’s visa, the Kremlin claimed that Russian businesses often encountered “unfair and unfriendly” actions when applying to come to the UK.
But Theresa May’s official spokesman said: “The prime minister has been absolutely clear that our argument is not with the Russian people, our dispute is with the Russian government.”
The changes introduced in 2015 mean that Abramovich will face tougher standards when reapplying for his new tier 1 visa, which he will have to do from outside the UK, probably in Russia.
Applications can be rejected if officials believe the applicant is not in control of funds, money has been obtained unlawfully, or the origin of funds means granting a visa will not be conducive to the public good.
There has been an 84% fall in the number of investor visa applications since the reforms were introduced.
There is no suggestion that Abramovich has been involved in any wrongdoing.
Abramovich, who was last seen publicly at a court hearing in Switzerland on Friday, missed Chelsea’s FA Cup final victory over Manchester United at Wembley on Saturday. The Saratov-born businessman has owned the club since 2003.
Tier 1 visas are thought to be held by about 700 wealthy Russians.
“We are currently taking another look at how the route operates and are undertaking further checks on investors who came to the UK through this route before the reforms were introduced,” a Downing Street spokesman said.
No 10 also confirmed additional checks had been taking place at private airfields after the Salisbury attack in March.
Abramovich’s visa is thought to have expired in April while he was out of the country and he has not tried to enter Britain since. His new application would have to be made from abroad, which means he will be subject to slightly more rigorous criteria than if he applied from within the UK.
Someone who knows Abramovich told the Guardian on Sunday that he had not been denied a visa but it was taking longer than usual to renew, and it was unclear why. A representative for Abramovich declined to comment, calling it a personal matter.
Russian officials complained on Monday that the UK was wielding the issuance or denial of visas as a weapon in the growing political standoff between Moscow and London.
Maria Zakharova, a spokeswoman for the Russian foreign ministry, told the Guardian in response to a question on Abramovich: “It’s obvious that for the British government both visas and the regulation of the media sphere are instruments of politics.”
It is not known where the billionaire is currently. He was last seen in public at the hearing at the district court of Sarine in Fribourg. A representative for Abramovich told the Guardian that he would not comment on his location.
Publicly available tracking data showed that a Gulfstream jet believed to be used by Abramovich flew from southern France, where he owns an estate on the Cap d’Antibes peninsula, to Switzerland on Thursday before the court hearing.
The same plane returned to southern France on Friday. It has not left since, according to the data. Public tracking data also shows that Abramovich’s luxury yacht, Eclipse, is currently moored off Antibes.
His Boeing 767 last flew from Moscow to Nice on 8 May, according to public data from the website FlightRadar24.
Chris Bryant, a Labour MP on the foreign affairs select committee, said he regarded the delay in granting Abramovich a visa as “a sign that the card of Putin and his allies is finally being marked”.
With the imminent passage through parliament of the sanctions bill, he said it would be possible to put those close to Putin on an open list either for sanctions or visa refusal. “It is best this is done as openly and transparently as possible, with carrots and sticks for good behaviour,” Bryant said.