The former chairman of Anglo Irish Bank said the bank and the Cowen Government should have realised the extent of the problems facing the lender before the Guarantee.
Alan Dukes' comments come after Central Bank Governor Patrick Honohan told the Banking Inquiry yesterday that Anglo should have been shut down, instead of covering it by the blanket guarantee.
Mr Dukes said the Northern Rock crisis and the problems facing German banks at the time should have alerted policy makers to the scale of the issues facing Anglo.
He believes a different course of action could have been taken – and far earlier.
"If the size of the problem on the asset side of the balance sheet had been realised, than I think a different approach would have been taken," he said.
"But the important point to make is that the different approach should have been taken well in advance of September 2008."