The Civil Aviation Authority received a complaint shortly before last weekend's fatal Fox Glacier crash.

Four Britons, two Australians, and local pilot Mitch Gameren died when their helicopter crashed into a deep crevasse last Saturday.

An inquiry is underway, with investigators from France, Australia, the UK and the USA involved.

One News reports the Civil Aviation Authority was investigating an allegation markings were being removed from the Fox Glacier landing area.

The authority isn't commenting on the reports.

The markings aren't legally required, but help pilots take off and land in snowy weather.