Gamers desperate to get their hands on Grand Theft Auto IV are being targeted by spam offering free entry to a 'competition' to win a PlayStation 3 and a copy of the much lauded game.

However, the illicit emails actually contain spyware and Trojans designed to steal personal financial information and attack victims' computers.

Grand Theft Auto IV was unveiled today for the PS3 and Xbox 360, and hundreds of avid gamers had queued up for the midnight release.

But some gamers have been left disappointed as stores have run out of stock, leaving scammers with a window of opportunity.

Spam-blocking firm ClearMyMail reported that more than half of the junk mail being blocked by its service this week is Grand Theft Auto IV related.

The vast majority offer the opportunity to 'win' a PlayStation 3 complete with the game on opening the email, and others invite the victim to pornographic websites which link to viruses.

Dan Field, managing director of ClearMyMail, said: "We are seeing unprecedented levels of spam in relation to the game.

"More than half of the spam our service is blocking is related to Grand Theft Auto, most of which contain viruses and spyware.

"Spammers are like conmen: they are the ultimate opportunists and like nothing more than to prey on the susceptible.

"My advice to anybody who receives these emails is to refrain from opening it, and to wait until they can legitimately purchase the game, even if disappointed by the record sales of this morning."