The two leaders of Uber in France were taken into custody Monday as part of a probe into their ride-booking app which has sparked violent protests from regular taxi drivers, AFP claimed, citing various sources.

The pair are believed to be Thibault Simphal,the director general of Uber France and Pierre-Dimitri Gore-Coty,the directorgeneral of Uber Europe.

According to BFM TV the pair are being investigated for “inciting illegal employment”, with the Interior Minister Bernard Cazeneuve having already suggested that the pair's insistence on rolling out UberPop was effectively encouraging individuals to break the law.

An investigation was opened in 2014 into the application used to put paying clients in contact with cheaper, private drivers who do not face the same regulations as cabbies.

The probe is focused on whether UberApp equates to “illegal organisation” of a system that allows drivers to transport clients for money, but who don't have to pay social contributions.

Sources also claim the investigation is looking into whether Uber are illegally collecting data on clients

Last week saw nationwide protests by French taxi drivers against UberPop across the country after which the French government vowed to crack down on the app.

Officially UberPop is illegal in France but it has been allowed to continue until France's constitutional court makes a final decision in September.

But regional authorities in France and the government are not willing to wait and have effectively declared war on the app, which counts more than 400,000 users in France.

Cazeneuve also pointed out that Uber could be guilty of the crime of “illicit transportation of people” under article 40 of the penal code, that could be punished by two years in prison and a €300,000.

It's not the first time authorities in France have acted against Uber.

In March this year the headquarters of the French branch of the US-based firm was raided at the request of the Paris prosecutor's office.

The company called the raid an “attempt at intimidation”.

Uber has filed complaints with the EU against France, Germany and Spain over their efforts to prevent the UberPop app.

Uber's American founder Travis Kalanick has said the system will create 50,000 new jobs in Europe this year, and help take 400,000 cars off the road by encouraging drivers to use taxis instead of their own vehicle.