Telegram boss and founder Pavel Durov has been placed under formal investigation as part of a probe into organised crime on the messaging app, French prosecutors say.
Mr Durov, 39, has not been remanded in custody – but placed under judicial supervision and has to pay a €5m (£4.2m; $5.6m) deposit.
Russian-born Mr Durov, who is also a French national, also has to show up at a French police station two times a week and is not allowed to leave French territory.
He was first detained upon arrival at Le Bourget airport north of Paris last Saturday under a warrant for offences related to the app.