Emirates Chairman Sir Tim Clark has likened Heathrow Terminal 3, where the airline flies in and out of, as looking ‘like a utilitarian structure, post-Second World War’.

The Telegraph reports Sir Tim, speaking at the International Air Transport Association (IATA) annual meeting in Dubai, said urgent investment is needed to catch up with rival airports.

Sir Tim said: “Heathrow is seriously lagging behind in many of its customer-facing functions.

“It’s an old airport and, all around, new airports are built employing the latest technologies to streamline their processes, whether it be security, check in, immigration or whatever, and making the whole thing a lot easier.”

He added: “The investment that needs to go into Heathrow must move at pace. You’ve got to invest, you’ve got to keep up with all the others.

“I’m hoping that the new owners will get that. But airports worldwide are not famous for spending money.”

Spain’s Ferrovial has agreed to sell its 25% stake in Heathrow to Saudi Arabia’s Public Investment Fund (PIF) and private equity group Ardian. The deal is contingent on Ferrovial and PIF finding buyers for another 35% stake in the airport.

A Heathrow spokesman said: “Every pound we want to spend on improving airport facilities needs approval from our regulator.

“Despite having our proposals cut back in the current regulatory settlement, we will still invest £3.6 billion upgrading our infrastructure over the next three years. We will continue to invest and to work with our airline partners to build an airport fit for the future.”