Getty ImagesPavel Durov founded Telegram in 2013Pavel Durov, the founder and CEO of messaging app Telegram, has been placed under formal investigation in France as part of a probe into organised crime on the messaging app.Prosecutors in Paris also said the 39-year-old billionaire has not been remanded in custody, but placed under judicial supervision, and has to pay a €5m (£4.2m; $5.6m) deposit.Mr Durov, who is also a French national, has to show up at a French police station twice a week and is not allowed to leave French territory.The actions from the prosecutors in France is the latest stage in this ongoing story, which has caused considerable shock in the world of technology.It is unprecedented for the owner of a social media or messaging platform to be arrested because of the way in which that platform is being used, and it has fuelled a debate about freedom of speech, accountability and the role of social media and messaging company bosses within all of that.Mr Durov’s lawyer, David-Olivier Kaminski, said Telegram complied in every respect with European digital regulations and was moderated to the same standards as other social networks.He said it was “absurd” to suggest his client could be involved “in criminal acts that don’t concern him either directly or indirectly”.Who is Pavel Durov?Mr Durov is a multi-billionaire who is originally from Russia.He founded the popular Russian social media company VKontakte.In 2014, Mr Durov left Russia after refusing to comply with government demands to shut down opposition communities on the platform. A year earlier, he had founded Telegram and now runs the firm from Dubai in the United Arab Emirates (UAE) where he now lives.He holds citizenship of the UAE and France, but Russia has said it still regards him as a citizen. After he was arrested, Telegram said Mr Durov travelled in Europe frequently.In an interview with the conservative US media personality Tucker Carlson in April, Mr Durov said he would refuse certain requests from authorities to remove content from his platform.He said: “Where we thought it would be crossing the line – it wouldn’t be aligning with our values of freedom of speech and protecting people’s private correspondence – we would ignore.”What is Telegram?Getty ImagesTelegram is one of the world’s biggest social media and messaging platforms along with Facebook, WhatsApp, Instagram, TikTok and WeChat.In July, Mr Durov claimed that Telegram reached 950 million monthly active users. It is popular in Russia and Ukraine, while pro-democracy groups in Iran and Hong Kong also use it.Telegram does offer end to end encryption, which means the messages can only be read on the device that sends them and the device that receives them, but this is not the default setting for the user. The big difference between Telegram and similar services like WhatsApp is the size of groups you can be in on Telegram.WhatsApp limits group sizes to 1,000 users whereas up to 200,000 can be in a group on Telegram.The platform has faced criticism that disinformation can spread in these huge groups.Critics have argued the platform has seen the sharing of conspiracist, neo-Nazi, paedophilic, or terror-related content.In the UK, the app was scrutinised for hosting far-right channels that were instrumental in organising this month’s violent disorder in English cities and cybersecurity experts say its moderation of extremist and illegal content is significantly weaker than other social media companies and messenger apps.Following Mr Durov’s arrest, Telegram said its moderation “is within industry standards and constantly improving”.It said it abides by European Union laws, including the Digital Services Act, which aims to ensure a safe and accountable online environment.”Almost a billion users globally use Telegram as means of communication and as a source of vital information,” the app’s statement read.”We’re awaiting a prompt resolution of this situation. Telegram is with you all.”What has been said about Durov’s arrest?In Wednesday’s statement, the Paris prosecutors said Mr Durov was put under formal investigation over alleged offences that included:Complicity in the administration of an online platform to enable illicit transactions by an organised gangRefusal to communicate with authoritiesComplicity in organised criminal distribution of sexual images of childrenIn France, being put under formal investigation does not imply guilt or necessarily result in a trial – but it indicates that judges consider there is enough of a case to proceed with an investigation.Elon Musk, the owner of X, has been defending Mr Durov for several days in a series of posts on his platform, formerly known as Twitter.He said moderation is a “propaganda word” for censorship, and called for Mr Durov’s release.Chris Pavlovski, the founder of a controversial video-sharing app called Rumble, said he had fled Europe following Mr Durov’s detention.Earlier this week Edward Snowden, the American whistleblower who now lives in Russia after revealing extensive internet and phone surveillance by US intelligence, said on X that Mr Durov’s arrest was “an assault on the basic human rights of speech and association”. He added: “I am surprised and deeply saddened that [French President Emmanuel] Macron has descended to the level of taking hostages as a means for gaining access to private communications. It lowers not only France, but the world.”After some details of the arrest had emerged, Vyacheslav Volodin – a prominent Russian politician and ally of Vladimir Putin – accused the US of being behind the arrest of Mr Durov.”Telegram is one of the few and at the same time the largest internet platforms over which the United States has no influence,” he said in a post on the platform.President Macron posted on social media on Monday that he had seen “false information” regarding France following Mr Durov’s arrest, and added: “This is in no way a political decision. It is up to the judges to decide.”