The proposed Olympic stadium in London will not be handed to a football club after the 2012 Games.
West Ham will not be leaving Upton Park for the Olympic stadium
If London's bid is successful, the stadium will form the focal point of the Olympic Park in East London.
The venue was expected to be used for football after the Games, with West Ham the most likely beneficiary.
But London mayor Ken Livingstone said: "Sadly West Ham won't get the stadium. We will scale it down to around 25,000 seats for an athletics facility."
Following the 2002 Commonwealth Games, Manchester City took over the lease for the main stadium.
However, Livingstone believes a lasting athletics legacy will be more attractive to members of the International Olympic Committee (IOC) when they evaluate London's bid.
He told the Guardian: "It will engage the IOC because it's the sort of facility that will attract world-class sporting events to London in the future."