Furious nature lovers descended on Leyton Marsh on Saturday, to protest about the giant Olympic basketball training hall due to be built there.

Around 70 people gathered on the marshes, and wove a large ribbon “no” into the fencing which surrounds the site behind the ice rink on Lea Bridge Road.

Despite widespread protest from park users and Upper Clapton residents, Olympic bosses won the right to build the hall a month ago, and ground preparation began this week.

More than 1,250 people signed a petition against the proposals, but supporters of the Olympic Delivery Authorities’ plans said the Games created special circumstances and the green space would returned to its original condition.

“Even if the building itself goes, the land will no longer be green belt and therefore cannot be protected from development,” said Caroline Day from the Save Leyton Marsh Group, which is campaigning to save the site.

Their Don’t be Harsh, Save the Marsh page on social networking site Facebook now has over 550 members and the hopes to take out an injunction against the works.

“The decision to use this Metropolitan Open Land was rushed through by four Waltham Forest councillors at short notice and there has been no Environmental Impact assessment to check what long-term damage this will have to the wildlife,” she added.

“Residents, dog-walkers and families are furious about the loss of precious green space, and they are forced to tramp all over the next field down for their walks, which is a Site of Special Scientific interest.”

An ODA spokesman said it would work to keep any impact on the Marsh to “an absolute minimum” and “restore the land to public use as soon as possible after the Paralympic Games”.

The Save Leyton Marsh Group is planning a rally there next Saturday, March 10, at 2pm.