Britain is the first country to ban 39-year-old Kabayev, Olympic champion in rhythmic gymnastics and past cover model for the Russian edition of Vogue magazine. Putin is 69 years old.
Officials say Kabayeva has become the board chair of the National Media Group, the largest private Russian media company and outlet for pro-war propaganda.
A statement from Britain’s Foreign and Commonwealth Office said, “There are allegations that he had a close personal relationship with Putin and that he had previously served as Putin’s deputy in the Russian Duma.”
Briefing reporters, British officials said that these friends and family members were not particularly skilled at their jobs but were “position engineers” to help Putin, suggesting that they were well-paid helpers “hiding in the shadows”.
The Kremlin has long denied a romantic relationship between Putin and Kabayev. A Russian newspaper reported in 2008 that the two had mysteriously closed down, although various reports said she was the mother of several of her children.
Kabayeva seems to have ended her athletic career when she became romantically involved with Putin. He later became a lawmaker for Putin’s ruling United Russia party and was one of the six torchbearers at the opening ceremony of the 2014 Sochi Winter Olympics.
According to an April report in the Wall Street Journal, the Biden administration debated imposing sanctions on Kabayeva but decided against it “at the last minute”, fearing that such a move would escalate tensions between Russia and the United States.
Putin has denied any involvement with Kabayeva, but British officials say measures have been taken to keep him out of the public eye since the start of the Ukraine war, such as the removal of his name from a Russian business website.
The list of British sanctions hit near Putin’s home. Among them is Kabayevar’s grandmother, the owner of a luxury apartment in Moscow called by the British government, and the ex-wife of the Russian president, the former First Lady of the Russian Federation, Lyudmila Ocheretnaya.
Also on the list is Eger Putin, the president’s first cousin; Mikhail Putin, a relative; And Roman Putin, the first cousin once removed.
Earlier, Britain and the United States imposed sanctions on Putin’s daughter, Maria Vorontsova, 36, and 35-year-old Katarina Tikhonova. They are his children with Ocheretnaya.
The British government has described individuals as “capable”.
UK Foreign Secretary Liz Truss said in a statement on Friday that “we are pursuing Putin’s luxurious lifestyle and exposing and targeting bad networks in his inner circle.”
Britain is leading the sanctions campaign, targeting more than 1,000 individuals and 100 entities, including 2 142 billion worth of oligarchs. UK officials say billions of pounds of assets have been seized in Britain.
Russia’s foreign ministry on Friday advised its citizens to refrain from traveling to the United Kingdom, warning visitors about the “extremely friendly course” that Britain has taken, and to “avoid financial losses and other potential problems.”
Seoul’s Brian Pitts contributed to this report.