On the current criteria, we've said very clearly, Heathrow expansion doesn't qualify.
Heathrow Airport's expansion could be scrapped under Labour plans to tackle the climate crisis by making the nation carbon-neutral by 2030.
Leader Jeremy Corbyn and shadow chancellor John McDonnell both signalled the controversial plans for a third runway may be blocked if the party wins the general election.
On Sunday, Mr McDonnell told the BBC's The Andrew Marr Show: "We set ourselves criteria, one of which was environmental impact, the other was also economic impact and social impact.
"On the current criteria, we've said very clearly, Heathrow expansion doesn't qualify."
Pressed if Labour would cancel the extension, he said: "At the moment it does not qualify based on the criteria we set out."
Later in the day, Mr Corbyn said: "It has to meet those tests and that is the reason why I opposed it when it last came to Parliament because, in my view, it did not meet those tests."
Other expansions across the country including in Manchester would also be considered under the criteria.
Parliament gave the go-ahead last year for the expansion of the London airport, which published its "masterplan" in June to build a third runway by 2026.
Sam Blewett is the PA political correspondent.