Computer users have been warned to beware of a fast-spreading email virus which promises a photograph of tennis star Anna Kournikova.

Experts said the new virus was spreading at twice the rate of Love Bug, which paralysed the email servers of more than 100 million users last year.

The email tempts users with the message: "Hi: Check This!", together with what appears to be a picture file labelled AnnaKournikova.jpg.vbs But clicking on the file produces no picture. Instead, the virus emails itself to every address in the user's address book.

Although the virus is not believed to damage computers, it could paralyse companies' computer systems with the huge volume of emails it creates.

Steve Gottwals, director of product marketing for F-Secure Corp, said: "It's an old virus concept but you put a pretty face and a nice pair of legs on it and people open it."

A recent report showed attacks by email viruses soared by 300 per cent last year. MessageLabs said it had detected and stopped 155,528 email viruses by the end of November - a rate of one every three minutes.

Anna Kournikova, 19, is the world's ninth-ranked tennis player.