French prosecutors on Wednesday, August 28, freed Pavel Durov, the founder and CEO of Telegram, from police custody after four days of questioning over allegations that the messaging app is being used for illegal activities, the Associated Press reported.

Durov was detained on Saturday at Le Bourget airport outside Paris as part of a judicial inquiry opened last month involving 12 alleged criminal violations.

"An investigating judge has ended Pavel Durov’s police custody and will have him brought to court for a first appearance and a possible indictment,” read a statement from the Paris prosecutor’s office quoted by AP.

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Allegations against the Russia-born Durov, who is a French citizen, include that his platform is being used for child sexual abuse material and drug trafficking, fraud and abetting organized crime transactions, and that Telegram refused to share information or documents with investigators when required by law.

Durov’s arrest in France has caused outrage in Russia, with some government officials calling it politically motivated and proof of the West’s double standard on freedom of speech, according to reports.

Durov founded Telegram with his brother in 2013. He 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.

The encrypted messaging app has close to one billion users.