The UK’s largest airport London Heathrow catered for six million passengers in August as its recovery was held back by its self-imposed cap on passenger numbers.

Saudi Arabia’s Public Investment Fund (PIF) and the Saudi-backed asset management firm Ardian have signed a £2.4bn deal for the Spanish infrastructure giant Ferrovial’s 25 per cent stake in the airport.

One other shareholder is now close to selling, with more likely to follow suit, according to a report in in The Sunday Times, which could see the oil-rich nation eventually gain majority control of the UK’s busiest airport.

David Simmonds, co-chair of the airport communities all party parliamentary group and Conservative MP for Ruislip, Northwood and Pinner, said he was “relieved that Heathrow, despite the impact of the pandemic, continues to attract interest from international investors.”

“Sovereign wealth funds have been key to the airport’s success and I am not surprised that Saudi Arabia’s Public Investment Fund forms part of this consortium. Heathrow stands at a pivotal moment in its development as it looks to recoup money lost over the last few years,” he added.

The PIF, which owns over £551bn in assets, has been one of the most active sovereign wealth funds in the world and recently acquired 10 per cent of the shareholding in the airport.

The Saudi state has also been investing heavily in tourism as it looks to promote a new image to the West. In March, it launched Riyadh Air, a new state-owned gulf carrier headed up by the former boss of Etihad Airways, Tony Douglas.

Heathrow declined to comment on speculation, while the PIF and Ardian did not respond to a request for comment.

Other major state-backed investment vehicles which hold stakes in Heathrow include the Qatar Investment Authority and the sovereign wealth funds of China and Singapore. Pension funds such as the Australian Retirement Trust and Canada’s Caisse de Dépôt also hold investments in the group.

The airport is at the tail end of a financial recovery after years of Covid-era lossmaking, with record passenger numbers in November.  But a mounting £16bn debt pile threatens to derail the revival, while the status of the long-delayed third runway proposal remains as yet unclear.

Simmonds added: “Any new investor must make clear their plans for expansion and development, with or without a third runway.”