The Davies Commission is alleged to be in support of an expansion at Heathrow, regardless of other possibilities.

This is according to a number of sources, including MP for Richmond Park and North Kingston, Zac Goldsmith. On his twitter page, the minister expressed concern that the report may be a forgone conclusion.

He said: "Osborne has spent public money on a review whose only purpose is to make a third runway decision [at Heathrow] look like it was reached independently."

Sources also told the Guardian that Sir Howard Davies, chairing the commission, was asked to expand the review to avoid such an exclusive focus, although this "could not be verified" by the paper.

Sir Howard is due to present an interim report on his findings next week, while the final document is not due until 2015.

However, it has been the subject of much debate as various groups are campaigning to provide the additional runway needed to support growing demand in Greater London.

Heathrow is one of the busiest hubs in the UK, receiving 5.4 million passengers in November alone.