George Osborne has ordered Prime Minister Theresa May to give a green light for a third runway at Heathrow, just days before the new government is set to announce its decision on airport expansion.
The former chancellor, who was sacked by May after six years in Number 11, said the case for expanding the west London airport was "overwhelming" and doubled down on his calls for the government to hurry up with a decision.
Taking to Twitter, Osborne said: "Time for a decision on airports and go for Heathrow. Economic case overwhelming; connects Northern Powerhouse; ensures Britain is open to the world.
"If we want Britain to be outward-looking, free-trading and global, we must expand the great airport that connects us to that world and that trade."
Read more: Expand both Heathrow and Gatwick
After a string of delays, the government is finally set to make a decision on airport expansion in the south east over the coming days. Last year the Airports Commission, after a lengthy and controversial investigation, came down strongly in favour of expansion at Heathrow as opposed to a second runway at Gatwick.
Osborne added: "We can consider Gatwick expansion. But not at the expense of Heathrow - and not in parallel or else, nothing will get built." It is not the first time Osborne has spoken out on the issue after telling May not to drag her heels over expansion just last week.
With a decision expected early next week both Heathrow and Gatwick have been stepping up their campaigns to try to influence the decision. Gatwick believes the findings of the Airports Commission are out of date, since their passenger numbers have already exceeded those used in the commission's economic forecasts, while the Scottish government recently backed expansion at Heathrow.