Emmanuel Macron’s plan for the biggest wave of French privatisations in a decade is under threat after opposition politicians took the unusual step of joining ranks to push for a referendum on the sale of Paris airports.

The centrist French president wants to sell the state’s controlling stake in Aéroports de Paris, the profitable operator of Charles de Gaulle and Orly airports, which are used by more than 100 million passengers each year. It would be among the biggest privatisation operations in French history, alongside Macron’s plans to sell other stakes in the national lottery as well as the gas and power group ENGIE.

The privatisation on the Paris airports is a crucial part of Macron’s modernisation plans for the French economy. A source close to the president said the state was not best qualified to run airport shopping and, with Charles de Gaulle ranked low for passenger experience, private managers could improve that. Profit from the sale – expected to be more than €7bn (£5.5bn) – would be redirected into a new investment fund for startup companies and technology, and would also help plug the national debt.

Macron’s national service sparks criticism from French left Read more

But political opponents accuse Macron of “flogging the family silver” and letting go of strategic state infrastructure. They say the UK, with its privatised Heathrow airport and privatised railways, illustrates a potential nightmare scenario of key transport infrastructure run for profit.

In an extraordinary move, a highly unlikely coalition of French politicians who are normally each other’s bitter enemies – ranging from communists and the hard-left to free-marketeers from Les Républicains, Nicolas Sarkozy’s rightwing party – have joined force against the Paris airports’ privatisation. They have been authorised by France’s constitutional council to make the first ever use of a people’s referendum mechanism introduced by Sarkozy in 2008. If they can get the signatures of 10% of the French electorate – 4.7 million people – within the next nine months, a national referendum will be held for or against the airports’ privatisation.

“It would be the first time the people would be able to decide on such a massive issue of privatisation,” said Laurent Russier, the communist mayor of Saint-Denis, north of Paris. At a time when gilets jaunes (yellow vests) anti-government protesters have called for more of a say in politics, and Macron has promised to listen more to citizens, a potential referendum is a test for French politics.

A race is now under way to gather the 4.7m signatures. “It will be extremely difficult but not entirely impossible,” said one campaigner, urging French voters from all regions and living abroad to sign. At least 17,000 signatures would be needed per day, but the government online platform for people to sign up is seen as difficult to use and prone to crashing. More than 200,000 people are estimated to have signed up since 13 June.

This week, the first public meeting to garner support was held in a crowded trade union building in Saint-Denis. In the French capital’s northern suburbs, Charles de Gaulle airport is a key employer. There were unusual scenes, with communist-voting trade unionists waving flags and applauding rightwingers whom they once would have jeered.

“The public interest comes first,” said Eric Coquerel of the hard-left party La France Insoumise (France Unbowed), arguing that it was not an anti-Macron political game, but a drive to protect state infrastructure. Marine Le Pen’s far-right National Rally was not invited to join the group, but she has urged her supporters to sign up to reach the 4.7m target.

On the right, politicians said Macron was using the same arguments as the Thatcher government over Heathrow’s privatisation in the 1980s – that there would be “better services provided for airline passengers”. Gilles Carrez, a rightwing lawmaker, said: “Many major airports have stayed under state control. The obvious exception is Heathrow and today the British regret the privatisation of Heathrow.”

“Pollution,” shouted a woman in the crowd, concerned over airport expansion like Heathrow’s third runway. The historian Patrick Weil said: “We’re in a third world war against the climate crisis, a battle which should be mobilising all of humanity. Selling Aéroports de Paris to the private sector is like handing arms to our enemy.”

The recent months of gilets jaunes demonstrations have highlighted privatisation in France – particularly the private companies which run French motorways. Last autumn, gilets jaunes protesters blockaded scores of motorway toll booths around the country, expressing anger at the rise in toll prices since privatisation in 2005.

Les Républicains MP Philippe Dallier said: “I bitterly regret supporting motorway privatisation and vowed to never make the same mistake [again]. That’s why I’m fighting Paris airport privatisation.”

Not everyone agrees. Gérard Lacher, a member of Les Républicains and head of the Senate, said the referendum drive amounted to a hijacking of democracy.

Among those who have already signed the petition for a referendum, Michel (surname withheld), 80, said: “A referendum is a good thing because I don’t trust politicians. The people should decide.”

Danielle (surname withheld) said: “Selling off Paris airports is one privatisation too far. We’ll end up looking like Britain in a Ken Loach film. An airport is not just about selling macarons or perfume – it’s security and the environment.”

Claire (surnamed withheld) had worked in baggage-sorting at Charles de Gaulle for 25 years. She said: “We need to keep it human. It’s not a profit machine.”