New Delhi, Aug. 4 -- SAN FRANCISCO - Telegram vanished from the Apple App Store on Monday night, briefly disappearing from the platform that gives iPhone users access to hundreds of millions of active channels, bots, and group chats. The outage lasted roughly forty minutes. Apple then put it back, and confirmed why it had taken it down.

The reason was child sexual abuse material. A user had posted it on the platform. Apple found it, pulled the app, then restored it after Telegram's developers removed the content and banned the offending account.

"We briefly removed Telegram from the App Store after our review found content that violates our strict guidelines prohibiting child sexual abuse material," Apple said in a statement provided to...