Three cases of suspected fraud linked to Norfolk County Council are being probed by police, while a potential fourth case has been reported to national investigators.
The council's investigative auditor is working with Norfolk Constabulary over the cases.
One of them is understood to stretch back to concerns that were first raised almost a decade ago, but council officers said "progress" is being made.
County Hall officers said: "Three previously reported investigations remain ongoing with law
enforcement at the point of reporting.
"We understand that progress on the investigations has been made during the period and the council's investigative auditor continues to work with law enforcement on these matters."
While the council has not revealed further details, it is understood one of those investigations relates to alleged fraud involving the council's 'county farms' estate - land owned by the authority and farmed by tenants.
The investigation dates back to 2015 - a time when independent auditors were brought in to look at the running of the estate.
In December 2020, two men - one in his 50s from Wisbech and one in his 40s from Downham Market - were arrested on suspicion of fraud.
The pair were questioned at King’s Lynn Police Investigation Centre before being released while the inquiry continues.
County Hall officers also revealed a further case of potentially fraudulent activity had been reported to Action Fraud, the national centre which investigates cybercrime and fraud.
The report about the ongoing cases was published just weeks after a deputy headteacher in a Norfolk school was sentenced for fraud, following an investigation by the council's anti-fraud unit.
Daniel Reynolds, 36, was deputy head at West Earlham Junior School when he created false invoices for food provided to disadvantaged pupils, even though it had not been bought but had instead been given free of charge by local organisations.
Reynolds, of Avocet Rise in Norwich, stole £8,520 to fund his betting habit, Norwich Crown Court heard, as he was sentenced to a 10-month prison sentence, suspended for 18 months, along with 300 hours of unpaid work.
Members of Norfolk County Council's audit committee were told about that case - and how a Proceeds of Crime Act investigation aims to recover the money Reynolds had defrauded the authority out of.
Brian Watkins, leader of the opposition Liberal Democrat group at County Hall, said: "These cases have been going on for some time. Sometimes these things do take a while, but, clearly, it would be good if they could be resolved as quickly as possible.
"It's also important, once they are resolved, that what has happened is reported back and that lessons are learned."
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here