East Surrey Conservative MP Peter Ainsworth has called on Crawley Borough Council to reject the application for 14,500m2 of additional floor space and a multi-storey car park to allow the airport to handle 40 million passengers by 2018 - an extra eight million per year.
"Any application of this kind is viewed with suspicion by local people who are understandably apprehensive about the incremental and unsustainable airport expansion," said Ainsworth.
Charlwood Parish Council, representing one of the local villages, made a submission to Crawley arguing that the effect of 20,000 extra flights and the traffic generated by the development "cannot possibly be minimal, negligible or anything less than highly significant".
Crawley planners are due to consider the application next week. However, campaigners hope that the Government Office for the South East will call it in and a public inquiry will be held.
The Gatwick Area Conservation Campaign has also written to the borough council citing its objections to the expansion proposals.
A spokesman for airport owner BAA stressed: "London Gatwick remains committed to sustainable and balanced growth and recognises the effect that the airport has on its neighbours."