Business leaders and an Airports Commission member also expressed dismay over the lengthy Government timetable for choosing between Heathrow and Gatwick.
The anger broke out after Downing Street appeared to signal clearly that it favours a third runway at Heathrow — but then revealed it will be up to 18 months before Parliament confirms the decision.
The most heavyweight intervention was from Sir John Armitt, who sat on the £20 million Airports Commission which in July last year recommended Heathrow expansion.
“It’s another delay and I’m not quite sure why it takes another year for that debate to take place,” he said. “There has been a lot of consultation. MPs are well up to speed on the situation. I hope that debate takes place in less than a year’s time.”
The Mayor of London said the timetable meant “unnecessary uncertainty” for investors. He added: “The Government’s decision to delay yet again deciding where to build a new runway will cause unnecessary uncertainty for British businesses already struggling with Brexit.”
The City of London Corporation’s policy chairman Mark Boleat said: “The Government needs to stop kicking the can down the road. Businesses have been waiting years for the decision and for them it is a massive issue which is affecting their ability to compete on the global stage.”
The Government strongly denied there was any delay, pointing out that the intricate process leading to a decision was first announced by Cabinet minister Patrick McLoughlin in February — although the former Transport Secretary did not explain at the time how long it would take overall.
A Downing Street official told the Standard: “It’s not a delay. The Prime Minister is taking the decision that has previously been dodged for more than half a century.”
The Cabinet decision will come next Tuesday — and No 10 believes it will be “the clearest sign yet that Britain is open for business post-Brexit”.
Colin Stanbridge, chief executive of London Chamber of Commerce and Industry, said: “This reported delay will be a massive blow to business confidence and, in all likelihood, damaging to the nation’s economy.
“We have had enough endorsements, investigations and recommendations. To be told that a final decision may now be in winter 2017-18 — six years after Sir Howard Davies was originally commissioned to do his inquiry — is actually not good enough.
“Given the Brexit uncertainty surrounding the UK at the moment, this was the ideal time to show strong leadership and signal that London is indeed open for business.”
Will Higham, director of campaigns at London First, said: “It is very encouraging that the new Government is about to make a decision on another runway in the South-East.
“But we could achieve £3.5 billion a year of extra exports, particularly to emerging markets, if we weren’t constrained by runway capacity.
“So the Government can’t drag its feet. It’s time to let Britain fly.”
Former Conservative Party chairman Grant Shapps MP warned against delaying another runway in the South-East as Britain seeks to build trading links in the post-Brexit era.
Speaking at Mayor’s Question Time, Mr Khan argued for Gatwick to be expanded instead of Heathrow. He went on: “Now more than ever businesses need certainty and stability in order to make investment decisions and to keep jobs in Britain. Instead they are getting dither and delay.
“Now it’s time to get on with building a new runway at Gatwick, which can be built quicker, cheaper, and without the years of legal and political battles that Heathrow clearly faces.”
But a Tory spokesman hit back saying: “We’re getting on with taking a decision and delivering for London and the whole country.
“As we do that we will follow a robust process, with consultation, that means additional capacity gets delivered.”