Campaigners have lodged an application for a judicial review against the £4bn Thames Tideway Tunnel.
Campaign body Thames Blue-Green Economy, led by Lady Dido Berkeley, claimed the government’s decision to award permission for the super sewer was unlawful.
Communities secretary Eric Pickles and environment secretary Elizabeth Truss last month granted development consent for the controversial project to be built and operated.
But Thames Blue-Green Economy claimed the government was in breach of public participation requirements under European and British Law.
It is calling for a halt to be brought to the Thames Tideway Tunnel project and for a more sustainable solution to be implemented, centred on local capture of rainwater.
“The TTT project will turn fresh rainwater into sewage at vast public expense and environmental damage,” the body claimed in a statement.
A separate group of experts led by campaigning body Blue Green UK chairman Graham Stevens last month told NCE it was looking at its own options for a legal challenge to the decision.
Stevens said in September that Thames Water’s consultation with local people was “not meaningful” and thus failed to comply with the Urban Waste Water Treatment Directive.
A spokeswoman for Thames Tideway Tunnel said today: “We are aware that Thames Blue-Green Economy has filed an application for a Judicial Review of the government’s decision to grant a Development Consent Order for the Thames Tideway Tunnel.
“Work continues on the project, business as usual”
A spokesman for the Department for Communities and Local Government said: “This is a challenging infrastructure project, but it is clear that the Thames Tunnel will help modernise London’s ageing Victorian sewerage system, and make the River Thames cleaner and safer.
“The substantive planning decision was made by ministers after careful consideration of all the representations.”
Thames Tideway Tunnel chief executive Andy Mitchell claimed when the development consent was granted last month that the tunnel would have captured 97% of the sewage that poured in to London’s river last year.