Setanta Insurance has gone into liquidation, leaving 75,000 Irish motor policy holders potentially without insurance cover.
The Central Bank is advising customers of the firm to arrange alternative cover "without delay".
A statement on the company's website says shareholders decided yesterday to wind up the company.
It is understood most of their business in Ireland relates to fleet insurance.
The company is incorporated in Malta and is not supervised by the Central Bank of Ireland, but authorities here say they will require Setanta to write to customers to advise them of the situation, and its implications for them.
The Central Bank is warning any claims will be subject to the liquidation process, so the company is not in a position to confirm that claims will be met in full.