The Audit Office is probing Northern Ireland's top Government office over more than £370,000 paid out without proper approval procedures.
Officials in Peter Robinson and Martin McGuinness' department have described repeated failures to obtain accounting officer permission before suppliers were secured as an "oversight".
But now Audit Office chief Kieran Donnelly has confirmed Assembly questions tabled by Traditional Unionist Jim Allister had uncovered more cases than his office was aware of.
And yesterday the Office of the First and Deputy First Minister pledged to co-operate with the inquiry - which could be finalised as soon as the end of this month.
The total of £373,716 relates to eight contracts awarded without authorisation by accounting officers - the highest worth £270,000 for a play and leisure policy.
Part of the controversy focuses on contracts awarded in situations where other potential suppliers were not given the opportunity to compete for the work. If any department intends to move away from the usual competitive tendering procedures, approval is needed from that department's accounting officer. In each case, permission for 'single tender actions' was got retrospectively.