A Bank of Ireland laptop with thousands of customers' details was stolen seven years ago in Co Kildare and clients were not informed.
Bank of Ireland says it is investigating an allegation that a laptop was stolen.
The development comes as the bank faces two separate investigations following the disclosure that laptops containing the details of 31,000 customers were stolen last year.
The theft happened in Bank of Ireland's Newbridge branch in 2001.
The laptop was used by an official from Bank of Ireland's life assurance division.
But the computer contained details of life assurance customers from branches in Newbridge, Kilcullen and Athy.
The laptop was not encrypted so the information could be easily accessed by hackers.
Sources have told RTÉ News that its theft was reported to line management in the bank. But customers were not informed.
The laptop had details of up to 4,000 Bank of Ireland customers.
These included dates of birth, addresses, bank account details, medical histories and investments held by customers.
In a statement issued this afternoon to RTÉ News, Bank of Ireland said it was investigating an allegation of a stolen laptop dating back to 2001.
A spokesman said the level of risk of fraud from information dating back seven years was remote.
Separately, the bank is currently sending letters to 31,500 customers who were affected by the theft of four laptops last year.
