The Central Bank has issued a prohibition notice to a former assistant manager of Rush Credit Union in Dublin.
It says Geraldine Harford is prohibited from carrying out any controlled functions, including pre-approval controlled functions, in any regulated financial service provider "for an indefinite period".
The order arises from a Central Bank investigation into Ms Harford's involvement in unauthorised transactions on accounts at the credit union.
Rush Credit Union is now in liquidation.
The prohibition notice was issued under the Central Bank's Fitness and Probity Regime.
But the bank says it is limited in what it can disclose due to ongoing criminal investigations.
Seana Cunningham is director of enforcement and anti-money laundering at the Central Bank.
"The Central Bank’s fitness and probity regime is in place to ensure that individuals performing key roles in regulated financial services firms are competent and capable, and act honestly, ethically and with integrity.
"The regime sets out the fitness and probity standards that those individuals must comply with, and places an obligation on the firms to ensure the compliance of their employees with these standards.
"The prohibition of individuals for an indefinite period of time from performing specific roles in financial firms is the most serious outcome under the fitness and probity regime."
This is the fourth prohibition notice issued by the Central Bank since its introduction.
A Central Bank review was launched following a €2m financial scandal surrounding the now-bust Rush Credit Union.