London 2012 Olympic organisers have been ordered to change the proposed mountain biking venue because it is not hilly enough to challenge the riders.
Courses must provide a stern test for the world's top riders
The request to move the venue from the Weald Country Park in Essex came after a visit by inspectors from the International Cycling Union (UCI).
Mountain biking was introduced to the Olympics at the 1996 Atlanta Games.
It is staged over a 40-50 km course for men and 30-40 km for women, with obstacles including rocks and streams.
"The UCI has asked us to find a course that meets new and challenging requirements that test the best mountain bikers in the world in 2012," said London 2012 Organising Committee spokeswoman Jackie Brock-Doyle.
"While this is disappointing news, we have agreed that, together with Essex County Council, we will look at other possible venues within Essex that meet the new requirements of the sport."