GOLD Coast Airport has rejected claims earthworks for the installation of the Instrument Landing System had been conducted outside of the approved construction footprint.

On Monday, Tweed Shire Council voted to write to the Federal and State Governments seeking an immediate investigation into the alleged damaging earthworks carried out 450m from the end of Runway 14, 150m more than what is stated in the ILS Major Development Plan.

Deputy Mayor Chris Cherry told the Tweed Daily News on Monday council was concerned the extra 150m of earthworks on NSW Crown Reserve was the exact same section of land that was in the original proposal for a runway extension.

GCA COO Marion Charlton said incorrect claims had been made about work being carried out on the NSW Crown Reserve, beyond the approved footprint.

Ms Charlton also rejected claims that the ILS project is related to a runway extension, since Gold Coast Airport is not planning to extend the runway.

But Mayor Katie Milne said the current earthworks does appear to have a "very similar footprint” similar footprint to the original runway extension proposal.

"The airport has had a significant environmental impact with the expansion activity that they have been undergoing,” Cr Milne said.

"We've asked (the Federal and State Governments) to treat it as a matter of priority.

"It's very unclear who's got compliance authority for the issue as council certainly doesn't have it.”