The warning is contained in accounts filed yesterday which also reveal that Hicks and Gillett paid £36.5 million in interest last year, contributing to a holding company loss of £42.6 million.
The American co-owners are in negotiations with banks RBS and Wachovia to refinance the debt, repayable on July 24, and are also seeking fresh investment from a third party.
The owners remain confident they will agree a deal with the banks, but in accounts for the club and its holding company, Kop Football (Holdings) Ltd, auditors KPMG warn of a 'material uncertainty' over the club's future.
'The group has credit facilities which expire on July 24. The directors have initiated negotiations to secure the replacement finance . and these are ongoing,' KPMG write. 'These conditions . indicate the existence of a material uncertainty which may cast significant doubt on the Group's and parent company's ability to continue as a going concern.'
KPMG's comments serve as a reminder of the crucial nature of the refinancing talks. The accounts also demonstrate that the profit made by the club, £10 million before tax in 2007-08, is swallowed by interest payable on the owners' loans.
Sources close to the owners said that KPMG's warning was a technical formality given the proximity of the refinancing date.
They also said Uefa has just renewed the club's licence to compete in the Champions League, a condition of which is that the club is a going concern.
In the accounts Hicks and Gillett insist: 'The directors have a reasonable expectation that the group will secure adequate resources to enable [it] to continue in operational existence.'
The accounts also show they have provided personal guarantees against £185 million of the debt.