Business secretary Vince Cable has waded into the UK airport expansion row by ruling out a third runway at Heathrow.
The senior Liberal Democrat politician said development of the London hub “was not going to happen”.
His comments came after the government confirmed a commission led by former Financial Services Authority boss Sir Howard Davies to look at ways of increasing the UK’s aviation capacity.
Cable’s intervention came as London Mayor Boris Johnson is set to announce a rival consultation into building a giant four-runway airport in the Thames estuary.
This came as a YouGov poll for the Sunday Times revealed that 37% of people believe a new estuary airport would be a better option for airport expansion against 26% who backed an extra runway at Heathrow.
More than a third of Londoners (44%) would prefer a new Thames estuary airport over a third Heathrow runway (24%).
Almost half of respondents agreed that the government is dithering over aviation capacity with 58% agreeing with Johnson’s description of the government’s attitude towards expansions as “fudge-arama”.
Cable told BBC One’s Andrew Marr Show the value of the Davies commission was to “look at the alternatives”.
The MP for Twickenham, said: “This is not a parochial little problem for southwest London. There are potentially two million people affected by this.
“There’s an absolute political commitment not to expand Heathrow.”
New transport secretary Patrick McLoughlin said the commission will identify and recommend to government “options for maintaining this country’s status as an international hub for aviation”.
He said: “This is a very difficult debate, but the reality is that since the 1960s Britain has failed to keep pace with our international competitors in addressing long-term aviation capacity and connectivity needs.”
The commission will publish an interim report by the end of next year with proposals on how to improve the use of existing runway capacity over the next five years and an assessment of what is needed to maintain the UK’s global hub status.
That will be followed by its final report after the next election in the summer of 2015.