A man has pleaded guilty to spreading the world's third most destructive computer virus.

Simon Vallor, 22, from Llandudno in Wales, admitted releasing the virus which affected 27,000 computers in 42 countries.

The virus was first seen on 5 December last year and spread via three emails entitled GoKar, Redesi and Admirer.

When the emails were opened, the virus spread by emailing the address list of each user.

Prior to appearing in court Vallor left a message about the case at his online diary here.

It stated: "Hopefully I'll get bailed again to appear in front of crown after [the] new year. I'd obviously wish for a suspended sentence but I think that's asking too much."

Graham Cluley, senior technology consultant for Sophos Anti-Virus, said that Vallor fitted the typical profile of a virus writer.

He added: "We're beginning to see more cyber-prosecutions which is good news for businesses and home computer users alike.

"Writing and distributing viruses is a serious crime. The cost of clearing up 27,000 infected computers in terms of lost man hours is substantial."

Vallor was traced via an internet access account registered at his home. His defence said that he had no previous convictions and was a man of good character.

A date has yet to be fixed for the sentencing hearing.