Rachel Reeves connected Wednesday said if Britain wants a beardown system the reply “can't ever beryllium 'no'” to projects that volition make growth.
The Mayor of London has threatened ineligible enactment if the enlargement goes ahead.
At a Bloomberg lawsuit astatine the World Economic Forum successful Davos, Switzerland, Ms Reeves said she would not remark connected "speculation", but pointed retired that the Government has already taken "big decisions" by backing enlargement plans astatine London City and Stansted Airports.
She added: "This was the occupation with the past authorities - that determination was ever idiosyncratic that said: 'Oh yes, of people we privation to turn the system but we don't similar that investment, we don't similar that upwind farm, we don't similar those pylons, we don't similar that airport, we don't privation that lodging adjacent us'.
"But the reply can't ever beryllium 'no' and that's been the occupation successful Britain for a agelong time, that erstwhile determination was a prime betwixt thing that would turn the system and thing else, thing other ever won.
"Now, of course, determination are different things that matter, but erstwhile we accidental that maturation is the fig 1 ngo of this Government, we mean it, and that means it trumps different things.”
In 2020 Heathrow won a Supreme Court situation to physique a 3rd runway and tin present question readying permission. But the Government inactive has the last accidental connected whether the task tin spell ahead.
He won a grounds 3rd word successful City Hall past twelvemonth aft campaigning against immoderate enlargement of airports successful the capital.
Eight furniture minister, including Energy Secretary Ed Miliband and Prime Minister Sir Keir Starmer, person besides antecedently spoken retired against a 3rd runway.
A machine representation of an expanded Heathrow aft the 3rd runway has been built
Heathrow
Sir Keir voted against the airdrome expanding successful June 2018.
Labour besides gained MPs successful ex-Tory strongholds successful westbound London astatine the wide election, including Boris Johnson’s erstwhile spot of Uxbridge and South Ruislip successful Hillingdon.
Peter Curling, a Labour Hillingdon councillor, said: “For the avoidance of doubt, The Hillingdon Labour Group remains resolutely and unequivocally 100% against a 3rd Runway astatine Heathrow.
“We privation a amended Heathrow, not a bigger Heathrow."
New CEO Kenton Jarvis said: "We invited the decisive enactment by the Government to turn the economy.
"We've ever said that aviation, the industry, is an enabler of economical growth.
"When it comes to Heathrow, I've ever thought Heathrow would acceptable our web of superior airports with large catchment areas.
"It would beryllium a unsocial accidental to run from Heathrow astatine standard - due to the fact that evidently close present it's slot-constrained - and springiness america an accidental to supply little fares for UK consumers that presently astatine Heathrow conscionable person the enactment of emblem carriers.”
Opponents of airdrome enlargement assertion boosting flights would beryllium damaging for the environment.
Alethea Warrington, caput of aviation astatine clime foundation Possible, said: "Approving airdrome expansions would beryllium a catastrophic misstep for a Government which claims to beryllium a clime leader.
"This immense summation successful emissions won't assistance our economy, and would conscionable promote the tiny radical of predominant flyers who instrumentality astir of the flights, further worsening the UK's immense tourism deficit."