Sir Chrisopher Hohn has built up a four per cent stake in Heathrow parent company Ferrovial worth £630m, according to the Sunday Telegraph.
Hohn bought a one per cent share in the Spanish construction and services company in May and has increased his influence since then.
It has now been revealed that Hohn has bought a further three per cent share in Ferrovial.
The tycoon revealed this month he was the largest individual backer of Extinction Rebellion thanks to £200,000 in donations.
The eco warriors organised mass protests over the past two weeks – with some aimed at London’s airports.
They describe themselves as a “decentralised movement” meaning protesters organised in small groups may carry out their own actions as long as they in line with the over all principals.
The group are opposed to air transport and have staged a number of protests at London airports.
A statement said: “The world is facing an unprecedented ecological crisis with scientists warning that we must urgently reduce emissions to avoid catastrophic climate change.
“Rapid reduction of passenger numbers and flights is required to limit global heating, but the number of flights being taken globally is increasing and airports are building more runways, with expansion plans all over the UK.”
Three flights at London City Airport were disrupted after a passenger lay on top of a British Airways plane on the runway and another forced a flight to turn around shortly after take-off.
Services at Gatwick Airport were also cancelled after a group of protesters were attacked by commuters at Canning Town Tube station.
This evening, members covered in fake crude oil turned out to protest an exhibition sponsored by BP at The National Portrait Gallery.
Hohn is one of the three largest investors in Spanish company Aena – the majority owner of Luton Airport.
His investment company, TCI, is the second-biggest investor in Eurotunnel owner Getlink.
Speculation is also rife that Hohn may be looking to significantly increase his share in Ferrovial.
More than 100 Extinction Rebellion-backing stars recently signed an open letter admitting they are climate change hypocrites.
The celebs, including millionaires Benedict Cumberbatch, Mel B, Daisy Lowe and Steve Coogan, confess their “high-carbon” lifestyles damage the planet and will continue to do so.
And cops are now investigating commuters after two protesters were pulled from the roof of a Tube train in east London.
James Mee, 35, and Mark Ovland, 36, were seen being pulled from the roof by furious passengers at Canning Town before being jeered and roughed up on Thursday.
The company’s UK-based construction company Amey is involved in an ongoing spat with Birmingham Council over a £2.7bn highways contract.
Ferrovial is now looking to sell Amey after it paid the council £215m to walk away from its contract.
Forty per cent of shares in Ferrovial are owned by the four sons of its late founder Rafael del Pino y Moreno.
A source told the Sunday Telegraph that the sons are acting separately in managing their respective stakes in the company.
They said: “In a go-private situation, a buyer does not need to win over each sibiling, whereas in the past, a buyer effectively required the support of the founding father.”
Ferrovial were contacted for comment and TCI declined to comment.