Businessman Roman Abramovich, 55, is said to be romantically involved with a 25-year-old TV presenter whose family has Ukrainian heritage.
The Chelsea FC owner Roman Abramovich was sanctioned last week for his links to the Kremlin after Russian President Vladimir Putin invaded Ukraine.
Foreign Secretary Liz Truss said in a statement released on the government website that they had targeted the oligarchs to "ramp up the pressure on the Putin regime and choke off funds to his brutal war machine".