New transport secretary Patrick McLoughlin has said he has “a completely open mind” on whether Heathrow will be allowed to build a third runway.
McLoughlin replaced Justine Greening, who was elected on an anti-Heathrow expansion platform, as transport secretary during a government reshuffle on Tuesday.
The Conservative-led coalition remains opposed to a third runway at the London airport, at least in principal.
However, members of the cabinet, including chancellor George Osborne, have refused to rule out the policy in recent days.
McLoughlin’s appointment as transport secretary suggest the government was preparing a change in policy, argued London mayor Boris Johnson earlier.
In a statement, the mayor said: “The third runway would mean more traffic, more noise, more pollution - and a serious reduction in the quality of life for hundreds of thousands of people.
“We will fight this all the way. Even if a third runway was built, it would not do the job of meeting Britain’s needs.
“If we are to remain Europe’s premier business hub we need a new four-runway airport, preferably to the east of London, that addresses the problem of aviation capacity before it is too late, and business is driven into the arms of our European competitors.
“It is time for Patrick McLoughlin to look at all the options, including bolder solutions that would deliver massive benefits in jobs and growth.
“And it is time for the government to level with Londoners. Are they in favour of a third runway at Heathrow or not?”