The UK's two biggest airports have "acted against the public interest" in failing to manage security queueing so as to avoid unacceptable delays, the Competition Commission said.
The commission said the situation at Heathrow and Gatwick airports can be remedied through a broadening and strengthening of existing service quality regulations.
Publishing the commission's views, the Civil Aviation Authority (CAA) said it would be "making proposals that remedy the adverse effects of the airports' conduct".
The commission's comments came in a report following its six-month inquiry into just how much airport operator BAA can charge airlines for using Heathrow and Gatwick.
The CAA said: "The CAA notes that the commission has found that Heathrow and Gatwick airports, in failing to manage security queuing and queue times to avoid unacceptable delays to passengers, crew and flights, have acted against the public interest, and that the commission proposes that these effects can be remedied through a broadening and strengthening of existing service quality regulations.
"The CAA cannot reject a public interest finding made by the commission and will be making proposals that remedy the adverse effects of the airports' conduct."
The Heathrow and Gatwick airport charges to airlines recommended by the commission are roughly in line with those already proposed by the CAA.
The CAA said it would consider the commission's report and then next month issue, for consultation, its own price control proposals for Heathrow and Gatwick for the five-year period starting in April 2008.
The commission report is separate from its continuing market investigation into the whole question of ownership of UK airports. The commission is required to report on this by the end of March 2009, but aims to do so earlier.
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Some airlines have called for a break-up of BAA's airport "monopoly". As well as running Heathrow and Gatwick, BAA is responsible for Stansted, Southampton, Edinburgh, Glasgow and Aberdeen airports.
