Fans face being ripped off ahead of the Russia World Cup, with tickets being listed on third-party websites for as much as £11,237, according to Which.
The consumer group have also warned travelling fans of counterfeit tickets being sold via secondary-ticketing sites.
Tickets originally priced at £300 on the official FIFA website have been listed for thousands of pounds. A pair of tickets for the England v Tunisia match, the Three Lions' opening game, were priced at £11,237 on one site.
Websites found selling tickets for the World Cup by Which? included; Stubhub and Ticombo.
Stubhub have since claimed that tickets were sold on their website due to a technical error.
Ticombo, however, have insisted that the selling of tickets complies with the rules of the free market.
Fans face being turned away
Stringent rules are in place to prevent the illegal reselling of tickets at the upcoming World Cup, with FIFA citing consumer protection and security as reasons for their implementation.
Fans wishing to sell their ticket require permission from football's chief body.
"You may not sell, offer for sale, resell, offer at auctions, donate Tickets, act as a commercial Ticket agent for another party or otherwise transfer your Ticket in any way without the specific prior written consent of FIFA," according to the organisation's official website.
The World Cup gets underway on June 14 (Photo: Shutterstock)
Fans wishing to resell their tickets must do so via an official resale platform.
As well as the threat of being sold counterfeit tickets, fans face thorough checks at the grounds, with identification required to enter grounds. Even if fans possess an official ticket they face being turned away at the turnstile.
As well as possessing a match ticket, supporters must hold a FAN ID, an identificiation document "required by the Russian authorities", according to FIFA.
Alex Neill from Which? has highlighted the risks of buying from an unofficial source.
"Football fans need to be aware that if they buy a World Cup ticket from an unofficial source, they risk paying inflated prices and potentially not getting into the game at all.
"If you don't want to risk watching the World Cup from the sidelines, you should only buy from the official Fifa reselling website."