Roman Abramovich expects his £1.5 billion loan to Chelsea to be frozen when the club's sale is carried out.
Fears are thought to have been raised in UK government that Abramovich could insist on his loan being repaid, which could jeopardise the entire sale process.
Russian-Israeli billionaire Abramovich is understood to have been advised that the UK government sanctions against him block his plans to write off Chelsea's debt.
The 55-year-old pledged to wipe out his loan to Chelsea when confirming he had put the Stamford Bridge club up for sale on 2 March, amid Russia's invasion of Ukraine.
Downing Street imposed sanctions on Abramovich on 10 March, claiming to have proved the business magnate's links to Russian president Vladimir Putin.
The terms of those sanctions have left Chelsea's parent company Fordstam Limited frozen, with the Blues operating under a special government licence.
And now Chelsea's long-term owner expects his loan to the club to be frozen when the sale is completed.
Abramovich vowed to create a new charitable foundation and donate all the proceeds of Chelsea's sale to aid victims of the war in Ukraine when initially putting the Blues up for sale.
The government is likely to divert the sale proceeds to charitable causes, but Downing Street chiefs could yet also freeze those funds.
Chelsea's sale needs to be completed by 31 May, when the government's special licence expires.
The Raine Group and Chelsea have both expected the sale to remain on course to meet that deadline.
Los Angeles Dodgers co-owner Todd Boehly's consortium bid is understood to have been selected as preferred bidder by the Raine Group, the New York merchant bank overseeing Chelsea's sale.
Boehly has edged ahead of bids from Martin Broughton and Steve Pagliuca to receive the preferred bidder status that inches the US tycoon ever closer to a takeover.
Jim Ratcliffe's last-minute bid on Friday has given pause to the entire sale process however, with Britain's richest man understood to be pressing on with his candidacy to buy the Blues.