Fears over Manchester United's financial future have increased after an investigation revealed substantial debts in another of the Glazer family's businesses.
In an investigation by investment analyst Andy Green, to be screened on the BBC's Panorama programme, it is claimed that the Glazers' First Allied Corporation - a company which owns and rents out shopping malls in the US - is heavily in the red.
The Daily Mail reports that £400 million is owed on 63 of the company's 64 malls and Green claims the issue amounts to a "real cash-flow problem for the Glazer family".
Green said: "The Glazers have called the US property market appallingly badly. They borrowed more money at inflated valuations right at the top of the cycle.
"These are people who tell us not to worry about Manchester United debt because they are great businessmen. In their core business in the US, they got it absolutely wrong."
The investigation also suggests the Glazers may have remortgaged 25 of their shopping centres in order to fund the United takeover.
Green said: "One has to ask: was the cash they put into Manchester United just debt but from somewhere else?"
Manchester United are currently £717 million in debt and, according to the Guardian, there has been £460 million in interest, fees and charges since the Glazers' takeover. The Daily Mail reports that the Glazers owe £70 million on their other business, NFL side Tampa Bay Buccaneers.
It is suggested that the debts could affect Sir Alex Ferguson's transfer budget this summer.