The regulator says Credit Unions are offering loans without checking if members can repay them.
The Central Bank says there's a "concerning number" of Credit Unions that need to improve how they are run and operate to a higher standard.
Details in the Irish Independent show the regulator made 700 visits to branches in the past six years.
It says many are offering loans without checking whether people can afford to pay them back.
It follows a damning report last week which revealed three in every ten prize draws were won by directors or members of staff.