A campaign group has said a report by the Airports Commission shows plans to build a third runway at Heathrow Airport face 'formidable' problems.

The Heathrow Association for the Control of Aircraft Noise (HACAN) sent a briefing to MPs and local authorities today (Monday, November 17), aiming to help explain the commission's findings, which were published last week.

HACAN said the commission's analysis showed the project could bring economic benefits, but also that there would be 'significant' obstacles.

Among the finding's highlighted by the group were:

- nearly 800 homes would need to be demolished;

- big improvements to the surrounding motorway network would be required, including putting sections of the M25 inside a tunnel, at an estimated cost of around £5billion;

- 70,000 new homes would be required, which the commission says the local authorities might find ‘challenging’;

- flooding could be a problem; and

- air pollution could exceed the EU legal limits.

HACAN chair John Stewart said: “The Airports Commission makes clear the problems of building a third runway at Heathrow remain formidable.

“My feeling is that, whatever economic benefits it might bring, the obstacles are so big as to frighten off any future government from giving a green light to expansion.”

The commission has been tasked with finding the best option for increasing airport capacity in south-east England.

The three options being considered are building a third runway at Heathrow, expanding one of Heathrow's existing runways, and creating a second runway at Gatwick.

Last week the commission published its analysis of all three proposals and opened its findings to a public consultation.

In its report, the commission admitted further work was required to fully assess the environmental impact of the proposals.

The airport says it has come up with contingency measures to minimise any negative impacts and that the expansion would create jobs.

Spokeswoman Paloma Aguilar said: “The Commission’s independent appraisal has made it clear that Heathrow could not only deliver over 41,000 more jobs for local residents by 2030 with expansion, but also ensure reduced levels of noise for those living near the airport.

"It says that ‘When compared to current noise levels, fewer people are predicted to be affected across all metrics.’

"Heathrow expansion would also result in a 'positive impact' on night flight noise in the future, according to the Commission, thanks to improvements to aircraft technology and the capability of early morning arrivals to land further to the west.”