Judges in France have placed Pavel Durov, the billionaire founder and chief executive of the Telegram messaging app, under formal investigation over the platform's alleged misuse by organized crime gangs.

Durov was put under judicial supervision and ordered to pay a 5-million-euro ($5.6 million) bail bond, but has not been remanded in custody.

The Russian-born tech leader, who also has French citizenship, must report to a French police station twice a week while the probe is ongoing and must not leave France.

The development follows his detention on Saturday at an airport north of Paris and four days of questioning over alleged offenses related to the Telegram app.

Prosecutors said on Wednesday that Durov is being investigated over potentially having been complicit in the administration of an online platform to enable illicit transactions by an organized gang, and for allegedly refusing to communicate with the authorities. He is also being probed for possible complicity in the organized criminal distribution of sexual images of children.

Being placed under formal investigation does not mean that the authorities believe Durov is guilty, but they think there is a good reason to proceed with a probe.

Durov's lawyer, David-Olivier Kaminski, said Telegram, which was founded in 2013, has consistently complied with European digital laws and regulations and is overseen in the same way as all other social media networks.

He said his client had not been involved "in criminal acts that don't concern him either directly or indirectly", the BBC reported.

Telegram, which is headquartered in Dubai, allows groups of up to 200,000 people to share information and comment on it, which is a far larger scale than those of its rivals such as WhatsApp, which tend to be limited to around 1,000.

Some Telegram users choose to send encrypted messages that can only be seen by the sender and recipient. The app has around 950 million registered users, and it is popular in Russia and Ukraine.

Act of intimidation

Telegram said the company and its founder have "nothing to hide", while the Russian government said the investigation could be seen as an act of "intimidation" against the enterprise for political purposes.

The BBC quoted Kremlin spokesman Dmitry Peskov as saying: "Given (Durov's) Russian citizenship, we are ready to provide all necessary help and assistance. But here the situation is complicated by the fact that he is also a French citizen."

Durov left Russia in 2014 after refusing to comply with the government's demand that the app block groups opposed to it. He subsequently obtained French citizenship in 2021 and has also become a citizen of the Caribbean nation Saint Kitts and Nevis and of the United Arab Emirates.

His arrest prompted a protest near France's embassy in Moscow over the weekend.

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