Olympics sponsor Visa has been accused of limiting visitors' access to cash at the Games by replacing 27 dispensers with just eight of its own outlets.
Visa confirmed it was replacing 27 ATMs at the various Olympic sites with eight which would run on its own system as part of its exclusivity arrangement as a sponsor.
Ron Delnevo of the UK Payments Council said the move appeared to be designed to "compel those visiting Olympic venues to use only Visa cards".
It understood Visa requested that the existing ATMs, which would have accepted all Link cards, were switched off and replaced with eight new machines which would only accept Visa cards.
It said ATMs would be switched off at the Excel Centre, Earl's Court, North Greenwich Arena, Wembley Arena, Wembley Stadium, Wimbledon, Old Trafford, St James' Park and the City of Coventry Stadium.
It raised concerns that visitors could run out of cash and have to resort to using Visa credit and debit cards, as no other cards would be acceptable.
Visa said visitors could bring cash with them, and pointed out that 115 million Visa cards were in circulation in the UK, meaning there was a "high probability" that most of those attending would have access to one of its cards.
The company said: "At every Olympic Games, Visa creates and manages the entire payment system infrastructure and network throughout all Olympic Games venues. Visa installs thousands of point-of-sale devices and a dedicated ATM network at every Olympic Games. Eight ATMs will be installed at London 2012 Olympic venues and this year, for the first time at an Olympic and Paralympic Games, contactless payment technology will be implemented across the event venues providing additional ways to pay."
Payments Council director Ron Delnevo said: "The Olympics are going to be cash-starved by design. This is plainly unacceptable in a world where 85%-plus of all transactions continue to be made using cash.
"The Olympics do not belong to any sponsor, however much money they have paid for brand awareness. The Games are meant to be a celebration of the sporting prowess of men and women from every corner of our planet. Sadly, it seems that the ideals of the Olympics now take a back seat whenever they get in the way of needs of commercial sponsors."