It has emerged that the chief executives of two State bodies were given severance payments without approval from the Department of Public Expenditure and Reform.
The payments - between 2011 and 2013 - were made despite a 2010 instruction from the department that it must approve such payments.
The Comptroller and Auditor General has reviewed dozens of severance payments totalling €18m, but the organisations involved have not been revealed.
Secretary General at the Department of Public Expenditure and Reform, Robert Watt, said that they had no choice but to agree to the payments in the two cases with chief executives.
"These were contracts that were entered into the late 1990s," he said.
"And when we were informed about the deal then, when the payments were being made, it was already based on the contractual arrangements that people had been signed into.
"So there was no leeway for the State at that stage but to pay, to make the payments.
"So we've tightened up the rules so that any contracts have to be cleared and approved by us in advance, so therefore the actual termination of payments then we can approve them."