London Mayor Boris Johnson has said that a new airport in the Thames Estuary - so-called Boris Island - would cost far less than is claimed in today's Airports Commission report.
According to the report, the scheme could cost between £82 billion and £112 billion and would result in airport charges around three times higher than those projected for Heathrow.
Johnson insisted the total cost would be around £50 billion - £20 billion for transport links and £30 billion for the facility itself, which he predicted could be funded from private investment.
Some believe today's report did not draw firm conclusions in order to avoid a politically divisive issue before the next election.
Expansion of Heathrow and Gatwick Airports are the shortlisted options being considered by a government report into airport expansion.
Heathrow is the third busiest airport in the world in terms of passenger numbers. It carried more than 69 million people in 2011.