Manchester United's owners, the Glazer family, have been asked to provide reassurances that club money will not be used to pay off the loans they took out to complete their Old Trafford buyout.
Investment analyst Andy Green, whose research was used in a BBC Panorama programme on the state of United's finances which aired on Tuesday evening, is demanding answers from the American owners over the state of their dealings.
The programme claimed the Glazers may have to use club money to pay off the £200million worth of 'PIK' loans they took out back in 2005.
Panorama claimed the family's debt has risen to over £1billion following escalating problems with their core US real estate business.
"I have no doubt you will have seen the new research about the state of the Glazer family's US real estate business," Green wrote in an open letter to club chief executive David Gill.
"I am also sure that the parlous financial state and weak cash generation of the business will have been as much of a surprise to you as it was to me.
"The family's spokesman has… stated that the club will not be sold, meaning the Glazer family need to repay their PIKs. Given the evidence now in the public domain about the profitability and levels of debt in the Glazer family's other businesses and hence the family's inability to pay off the PIKs from their own resources, it seems the only possible source of cash to do so is Manchester United itself.
"In light of these revelations, can you assure United supporters that none of club's current or future cash will be used to repay the Glazer family's PIKs?"