French opposition lawmakers from the right and left are combining efforts to try to block President Emmanuel Macron's plan to privatize Paris airports.

France's lower house of parliament, the National assembly, definitively adopted on Thursday a measure allowing the government to privatize the group operating Paris' three airports, Aeroports de Paris, or ADP.

Opposition lawmakers from the left and right launched a long process that could ultimately lead to a popular referendum under a procedure introduced in 2008. The Constitutional Council will examine their request.

The state owns 50.6% of ADP and did not specify how much it would sell.

The centrist government says the move would raise 10 billion euros ($11.3 billion), money that would help finance investment in new technologies.

Opponents say Paris airports are strategic hubs.