M4 Newport relief road concern by Friends of Earth Cymru
Friends of the Earth Cymru says it has not seen any evidence to suggest a need to build an M4 relief road south of Newport.
Chancellor George Osborne said he would shortly give details of "impressive" M4 relief road plans.
But FoE director Gareth Clubb said the pressure group has not seen a "shred of evidence" it was needed.
Public consultation on building a relief road south of Newport will begin in September.
Mr Clubb outlined his concerns to Bethan Rhys Roberts on BBC Radio Wales.