Unlike the Irish Blood Transfusion Service laptop stolen in New York last February the data on the four Bank of Ireland laptops was not encrypted.

The use of encryption means the data is concealed using a secret algorithm or "key" which means it is difficult, although not impossible, for anyone other than the authorised owner to access the information.

Conor Flynn, a director of RITS Information Security, describes the implementation of encryption as "trivial" and estimates the cost per laptop as being between €30-€100 depending on which technology is adopted. "It would be significantly cheaper when you are talking about the volume that Bank of Ireland would need," says Mr Flynn.

"Encryption is not the silver bullet that everyone makes it out to be," says Brian Honan, a director of BH Consulting. "Encryption is only as strong as the password the user chooses."

Experts have also questioned whether sensitive data should have been stored on the laptops at all.