A number of other high profile companies are now thought to have been caught up in the hacking incident at Clare firm "Loyalty Build".
Some customers of Clerys, Centra, Stena Line and Postbank may have had their details compromised.
However, the numbers involved are far smaller, believed to be in the hundreds.
The hack - blamed on "sophisticated criminals" - happened in mid October.
The company involved - LoyaltyBuild - is expected to release a further statement this evening.
