Thousands of ICQ users affected by account deletion

Up to two thousand ICQ users are thought to be affected by a glitch which has left many unable to access the popular messaging service after finding that their UIN (Unique Identification Number) was no longer allowing them access.

The UIN is the only permanent piece of information identifying each user, since usernames and email addresses can be changed at will. Therefore, the affected users - many of whom have posted their complaint on the ICQ message boards - are unable to enter the site at all.

"I've got the same problem. My account is deleted, too and I don't know why....please please help me! My number is so important for me! I need my list back!" one anonymous user said.

ICQ was founded in 1996 by the young Israeli company Mirabilis. Since then, it has enjoyed worldwide success and is the tool of choice - surpassing MSN Messenger for example - for instant communication on every subject imaginable. It was then acquired by AOL two years later for $407m - a testament to its rapid growth.

The early UINs were short, memorable numbers and have been known to change hands for exorbitant prices on Ebay. There have been many security problems reported with ICQ in the past, with users' accounts being hacked into and stolen on a regular basis. Nonetheless, the number of people reporting that their account has "disappeared" today is unprecedented, and will leave many angry.

AOL so far has not commented, nor have any messages been addressed on the ICQ boards.