Lawyers have branded the council's decision to give the go-ahead to a controversial in incinerator "unlawful".
Lawyers representing Croydon man Shasha Khan have served a letter on Sutton Council saying they believe the council broke the law in giving planning permission for an energy recovery facility (ERF) in Beddington Lane.
The ERF will burn rubbish from Sutton, Croydon, Merton and Kingston and convert it into energy and heat for nearby homes. Planning permission was granted last year and a legal agreement was reached earlier this month meaning - pending a judicial review - the project can now go ahead.
However law firm Deighton Pierece Glynn, which represents campaigner Mr Khan, has sent a letter to the council warning that if it does not withdraw the planning permission it will file for a judicial review
Deighton Pierce Glynn has given the council two weeks to respond to the request.
Mr Khan's solicitor Sue Willman said "We believe Sutton has acted unlawfully.
They have failed to demonstrate the very special circumstances needed to build an incinerator on Metropolitan Open Land which is the London equivalent of Greenbelt.
"Mass burn incineration is an outdated and unsustainable technology and there are major questions about its effect on people’s health.
"This case is just one of many which local people are bringing across the UK to stop an army of waste incinerators being built when councils should be focused on cleaner renewable energy and recycling."
Campaigners fear the incinerator will create harmful pollution but the council and the Environment Agency have dismissed the claims, saying any emissions from the plant will fall within acceptable levels.