A report from the House of Commons Environmental Audit Committee has advised the British government not to allow the building of a third runway at London Heathrow unless strict environmental criteria can be met.
In the latest stage of a long-running debate, the Airports Commission published a report backing a third runway in July.
However, the committee said firm plans to deal with climate-changing emissions, air quality and noise need to be put in place.
A final government decision is expected by the end of the year.
Huw Irranca-Davies, chairman of the committee, said it would be “irresponsible” to postpone dealing with the environmental impact of expansion at Heathrow.
He added: “If the government decides to accept the commission’s recommendation for a third runway in principle, we will seek assurances from the secretary of state for transport that environmental conditions will be met before it is given final approval.”
The MPs said the airport had to show that an expanded Heathrow would be less noisy than it is with two runways.
Their report also called for Heathrow to say it would cover the costs of surface transport improvements.