A deadly virtual plague has broken out in the online game World of Warcraft according to reports on the BBC.

Although limited to only a few of the game's servers the numbers of characters that have fallen victim is thought to be in the thousands.

Originally it was thought that the deadly digital disease was the result of a programming bug in a location only recently added to the Warcraft game.

In the last week, Blizzard the games developers added the Zul'Gurub dungeon which gave players a chance to confront and kill the fearsome Hakkar - the god of Blood.

In his death throes Hakkar hits foes with a "corrupted blood" infection that can instantly kill weaker characters.

The infection was only supposed to affect those in the immediate vicinity of Hakkar's corpse but some players found a way to transfer it to other areas of the game by infecting an in-game virtual pet with it.

This pet was then unleashed in the orc capital city of Ogrimmar and proved hugely effective as the Corrupted Blood plague spread from player to player.

Although computer controlled characters did not contract the plague, they are said to have acted as "carriers" and infected player-controlled characters they encountered.

Blizzard tried to control the plague by staging rolling re-starts of all the servers supporting the Warcraft realms and applying quick fixes.

However, there are reports that this has not solved all the problems and that isolated pockets of plague are breaking out again.