Celtic's debts increased by more than £4m sterling in the last financial year as a result of 'unacceptable results' under former manager Tony Mowbray.
The Scottish Premier League club posted a loss before taxation of £2.1m, and also showed a 15% drop in annual turnover, after making a profit of £2m the previous year.
Turnover dropped to £61.7m and net bank debt rose to £5.85m in the year up to June 30, according to the club's preliminary financial results.
Celtic chairman John Reid claimed the team's struggles under Mowbray, who departed in March after less than a season in charge, were partly to blame for the financial downturn.
'Just as football and financial strength are essential partners in progress, so too they affect each other adversely when we are not succeeding as we should,' Mr Reid said.
'Thus the combination of the financial/economic recession and disappointing football results have taken their toll in this year's report,' he added.
