Pavel Durov, billionaire founder and CEO of the Telegram messaging app, was arrested at the Bourget airport outside Paris on Saturday evening, TF1 TV and BFM TV said, citing unidentified sources.

TF1 and BFM both said the investigation was focused on a lack of moderators on Telegram, and that police considered that this situation allowed criminal activity to go on undeterred on the messaging app.

Telegram did not immediately respond to a Reuters request for comment. The French Interior Ministry and police had no comment. Russia, which has in the past tried to ban Telegram, said it was taking steps to "clarify" Durov's situation.

What is known about Durov and Telegram:

* Russian-born Durov, 39, is founder and owner of messaging app Telegram, a free to use platform that competes with other social media platforms such as Facebook's WhatsApp, or Instagram, TikTok and Wechat. The platform aims to surpass one billion active monthly users within a year.

* Telegram is influential in Russia, Ukraine and the republics of the former Soviet Union. It has become a critical source of information on Russia's attack on Ukraine, used heavily by both Moscow and Kyiv officials. Some analysts call the app "a virtual battlefield" for the military conflict.

* Durov, whose fortune was estimated by Forbes at $15.5 billion, left Russia in 2014 after refusing to comply with government demands to shut down opposition communities on his VKontakte social media platform, which he sold.

* Durov became a French citizen in August 2021. He moved himself and Telegram to Dubai in 2017, and according to French media he has also received United Arab Emirates citizenship. He is also a citizen of St. Kitts and Nevis, a dual-island nation in the Caribbean, according to media reports.

* Russia began blocking Telegram in 2018 after the app refused to comply with a court order to grant state security services access to its users' encrypted messages. The action had little effect on the availability of Telegram there, but it sparked mass protests in Moscow and criticism from NGOs.

* Telegram's increasing popularity, however, has prompted scrutiny from several countries in Europe, including France, on security and data breach concerns. In May, the EU tech regulators said they were in touch with Telegram as it neared a key usage criterion that could see it subject to more stringent requirements under a landmark EU online content legislation.

* "I would rather be free than to take orders from anyone," Durov told U.S. journalist Tucker Carlson in April about his exit from Russia and search for a home for his company which included stints in Berlin, London, Singapore and San Francisco.