British Airways (BA) top boss Willie Walsh has said it will not support the "outrageous" costs of building a third runway at Heathrow Airport.

Chief executive of International Airlines Group (IAG), which owns BA, Iberia and Vueling, said the costs of the £17bn expansion plan "does not makes sense to the airline", according to Reuters.

“We think the costs associated with the third runway are outrageous and certainly from an IAG point of view we will not be supporting it and we will not be paying for it,” he said.

“We’re not going to support something that increases our costs.”

Mr Walsh made the comments following the release of IAG’s half-yearly financial results on Friday (July 31) where it announced an operating profit of €555m - up from €230m last year.

The former CEO of BA previously said he believes "a third runway will never be built" and "has been planning for life without".

BA currently carries almost 40m customers a year on its fleet of more than 280 aircraft around the world.

A spokeswoman for Heathrow said expansion was critical to the future of Britain’s economy.

“It is the only way the whole nation will be connected to all of global growth,” she said.

“The Airports Commission has confirmed that expansion can be financed and with low-cost airlines such as easyJet already committing to provide routes from Heathrow, it is clear that operating costs from the airport will be competitive.”

However, Gatwick Airport’s CEO Stewart Wingate said it was no surprise that BA had come out against expansion.

Mr Wingate added: “For the huge costs of a third runway at Heathrow you could build Gatwick, have all the benefits, and billions left to invest around the country.

“Taken together with Heathrow’s own rejection of the environmental conditions and the expert view that the Davies air quality consultation is fundamentally flawed, it is clear that the Heathrow hurdles are higher than ever.

"Choose Heathrow and it will be Groundhog Day - nothing will happen. Choose Gatwick and Britain can finally get on with it.”