Officials admit the council has forked out huge sums of money to contractors for work that is now under investigation due to allegations of favouritism, mismanagement and corruption.
Five staff have been sacked and up to 15 more are believed to have been suspended in the wake of a probe that has been running for almost two years, and now involves external consultants and the police.
The figure, confirmed by the council’s head of services, Mark Turley, does not include bills that were settled but have been challenged since the scale of the allegations into the council’s property department emerged.
More than 870 separate complaints are being investigated.
Mr Turley said: “The independent investigation we commissioned uncovered the scale of the outstanding amount.”