The ticket seller is on a sponsored link as "Official World Cup Site"

The website shows up as "official World Cup site" as the first sponsored link on search engine Google, when anyone enters Rugby World Cup or RWC.

A spokesman for the Rugby World Cup said creating an unofficial ticket purchasing mechanism was "illegal".

Viagogo said the website was not its own, and was investigating how it came to be connected with it.

The tournament is hosted by France, although matches will be played in 10 cities, including four games in Cardiff.

We are investigating it. We do not sell anything illegal. Viagogo spokeswoman

Fans have been advised by the International Rugby Board (IRB) to buy their tickets to all the games from official sources.

Otherwise, they run the risk of having them cancelled, being refused entry to games, or even expelled from the stadium, they are warned.

Buying from unofficial websites - including online auctions - could be seen as ticket re-selling, which is against the rules of sale.

'Investigating'

Greg Thomas, spokesman for Rugby World Cup, said the website in question was "particularly blatant".

"We are not very happy about it and that is why we have put it in the hands of our rights protection team.

"They have created an unofficial ticket purchasing mechanism. That is illegal. They are claiming a status which is totally incorrect.

"We have told members of the public whenever possible that they should buy tickets from official sources only. You cannot get access to grounds otherwise."

A spokesperson for Viagogo said: "www.rugby.world-cup-2007.co.uk is not a viagogo website and we are looking into how we could have been connected to it.