It is understood that English Nature, which control Sites of Special Scientific Interest (SSSI), is to draw up a new agreement with the farmer, Justin Harmer, who owns Offham Marshes near Lewes, East Sussex. Friends of the Earth (FoE) said that the move was made following pressure on Michael Meacher, environment minister, to intervene.
The marshes are adjacent to Offham Down, another SSSI also owned by Mr Harmer, which became the focus of a row during the general election after it was ploughed up to take advantage of European subsidies to grow flax.
Matt Phillips, of Friends of the Earth, said the reprieve for Offham Marshes was good news for wildlife a celebratory picnic would be held tomorrow. The site is home to one of the most significant populations of toads, frogs and newts in the country.
But, he said, 300 out of the 6,500 SSSIs in Britain were damaged every year and there needed to be better legal protection for the country's most important wild places. "We want to make sure that nothing like this can happen again."
Another SSSI in Porth Ceiriad, Gwynedd, has just been damaged after a management agreement was allowed to lapse. An unusual feature of the remote coastal site was a sand dune perched on the cliff top where top soil has now been dumped.
A Department of the Environment spokeswoman said the Mr Meacher has asked officials to begin open-ended discussions with interested parties about what changes to the law might be necessary to promote better management of SSSIs and increase protection for them.