Unison.ie has acknowledged that a security breach in its online registration system would allow users to view the personal profiles of other registered users when they were automatically logged onto the website.

One disgruntled user contacted Unison, which has since apologised for the error.

It has also disabled the "remember" function on the account, which was identified as the problem area.

This "remember" facility is designed to allow visitors to log onto their personal page automatically, without entering an e-mail address and password on each visit.

A spokesman for Unison.ie confirmed that a number of complaints was received and that the issue was "resolved immediately". He described the programming error as one with "a one in a million chance of occurring".

This issue is likely to further undermine consumer confidence in internet security.

This event is similar to a security breach that occurred in Eircell two years ago.