Opponents of a proposed airport expansion in east Kent have taken their arguments to a body that advises on planning policy for the South East.
The expansion is supported by the Friends of Lydd Airport group
The Keep The Marsh Special Alliance is against plans for an extended runway and terminal at London Ashford Airport.
Representatives have attended a meeting of the South East England Regional Assembly (Seera) in Maidstone.
They claim the plan is unacceptable environmentally which the airport, in Lydd, denies.
Seera is holding an Examination in Public (EiP) of its South East Plan - a draft 20-year vision for the future of the region.
Its contents will ultimately guide local councils on planning and other policies.
The EiP is currently sitting in Maidstone, where the airport protesters took their case on Tuesday.
They claim environmental issues far outweigh the positive impact of job creation.
Malcolm Dyer, from the Keep The Marsh Special Alliance, said: "They [London Ashford Airport] want to be a regional player in the growing aviation market.
"We're talking millions of passengers and cars, huge congestion, and this area is the biggest centre for bird migration and bird conservation in south-east England."
But airport spokesman Robin Gordon argued: "I think we've looked at our environmental responsibilities very, very carefully.
"We're talking about lengthening the runway by some 450m (1,476ft) - it's over a rough area of farmland and it's very remote from the bird ranges at Dungeness."
Planning applications concerning the runway and passenger terminal have been submitted to Shepway District Council.
A council consultation on the airport plans runs until 5 March.