London 2012: Residents oppose basketball centre plans
Hundreds of residents have signed petitions against Olympic organisers' plans to build a temporary basketball training centre on Leyton Marshes.
Local resident Jessica Tibbles said: "You can't really regenerate green-belt land. You need to leave it alone."
But The Olympic Delivery Authority (ODA) said: "This is a once in a lifetime opportunity for London."
East London's Waltham Forest Council said it would consider the planning application at a meeting on 7 February.
If the plans are approved, the basketball centre, which will contain two basketball courts, would be under construction or in use between March and October.
A number of separate groups have set up petitions against the plans, including residents organisation Millfields Users' Group, which has collected more than 200 signatures.
Leyton Marshes are classed as Metropolitan Open Land (MOL), which generally means they cannot be developed.
However, the Olympic organisers said the Games were in the national interest, hence the land could be built on.
The marshes are one of four open spaces near the Olympic Park that the ODA plans to build on this summer.
Ms Tibbles said: "It's the most important place to the community and it's priceless."
But the ODA's director of infrastructure and utilities Simon Wright said: "This is a once in a lifetime opportunity for London and we do have to get it right.
"In order to support the Olympics, we need those areas on a temporary basis and we've agreed with the owners and local authorities to ensure the impacts are minimised and are investing in the long-term future of them after the Games."