Pavel Durov, the founder and CEO of Telegram, is under formal investigation related to illicit activities on the messaging app.
French authorities have also prohibited him from leaving the country, CNN reported.
Notably, Pavel Durov, who had an arrest warrant issued against him, was detained by the French authorities at an airport outside Paris, CNN had earlier reported.
Officers from France's anti-fraud office, attached to French customs, took the French-Russian billionaire into custody on Saturday evening after he arrived at Bourget Airport on a flight from Azerbaijan, according to CNN affiliate BFMTV.
Durov was wanted under a French arrest warrant due to the lack of moderation on Telegram, which allegedly led to the platform being used for money laundering, drug trafficking and sharing pedophilic content.
Earlier in the day, Durov was released from police custody in France and was transferred to court for questioning, CNN reported.
Laure Beccuau, the Paris prosecutor, said in a statement that Durov had been ordered to pay bail of $5.5 million, and was released but must check in at a police station twice a week, according to The New York Times.
Beccuau also asserted that Telegram has featured in several criminal cases in France in connection with child sexual abuse, drug trafficking and online hate crimes, but has shown a 'near-total absence' of replies to requests for cooperation from prosecutors.
Prosecutors around France, along with legal authorities in Belgium and other European countries, 'have shared the same observation', Beccuau said, leading organised crime prosecutors to open a probe in February on the 'potential criminal liability of executives at this messaging platform', The New York Times reported.
Beccuau further said that if Durov is convicted, he could face up to 10 years in jail.
Durov is being probed for several suspected offences related to criminal activity on the messaging app, including complicity in illegal gang transactions, laundering of crimes in an organised gang, and refusal to communicate information to authorities, as per the French prosecutor's statement, CNN reported.
Notably, France issued an arrest warrant for Durov on charges of complicity in drug trafficking, crimes against children and fraud due to the lack of moderation on Telegram and his failure to cooperate with law enforcement, the Moscow Times reported, citing French local media.
The Russian-born founder of Telegram, which he says boasts over 900 million users, is currently based in Dubai. He became a naturalised French citizen in August 2021.
Durov, who is also the founder of the VKontakte social network, left Russia in 2014 after he refused to share VKontakte users' data with Russian security services.
Later, Russia unsuccessfully attempted to block Telegram over its refusal to provide users' online communications to security services.
