Heathrow is facing growing opposition to its proposal to raise passenger charges well above the rate of inflation to fund a £3 billion investment programme.
The British Air Transport Association (BATA) joined airlines in calling for the airport to be forced to reduce charges instead.
BATA chief executive Simon Buck said: "BATA supports improving the passenger experience at Heathrow. However, we believe this can be done without a repeat of the incredibly steep price rises we have seen in airport charges in the last few years.
"Prices at Heathrow are triple the level they were ten years ago and Heathrow is already the most expensive hub airport in the world."
Heathrow said today it was applying to the Civil Aviation Authority for permission to raise passenger charges from £19.33 a head to a maximum of £27.30 in 2018/19 (see earlier story).
However, BATA said: "In the current economic climate other businesses, in private and public sectors and especially airlines, are making savings and delivering on less money.
"Airports should not be exempt from that and we call upon the CAA to use its regulatory powers to ensure there is a real terms reduction in charges applied to each passenger."