The encrypted messaging app Telegram was mysteriously removed from Apple's App Store last week for a number of hours. At the time, little was known about the reason why, except that it had to do with "inappropriate content." According to a 9to5Mac report, Apple removed Telegram after the app was found serving up child pornography to users.

A verified email from Phil Schiller details that Apple was alerted to child pornography in the Telegram app, immediately verified the existence of the content, and removed the app from its online stores. Apple then notified Telegram and the authorities, including the National Center for Missing and Exploited Children. Telegram apps were only allowed to be restored to the App Store after Telegram removed the inappropriate content and reportedly banned the users who posted it.

"The App Store team worked with the developer to have them remove this illegal content from the apps and ban the users who posted this horrible content," the email reads. "Only after it was verified that the developer had taken these actions and put in place more controls to keep this illegal activity from happening again were these apps reinstated on the App Store."

That process took a few hours, but then Telegram apps reappeared in the iOS app store with new safeties that developers believe will prevent illegal content from being pushed to users. Apple's email states that the company will take "swift action" whenever it's alerted to inappropriate content in any app available on the App Store.

Since Telegram is a messaging app with end-to-end encryption, it's unlikely that the content in question originated from direct messages between users. It's possible that the child pornography came from a Telegram plugin, but neither Apple nor Telegram has revealed the source of the inappropriate content.

While this is the first time Telegram was removed from the App Store for such a violation, the platform has had issues with violent and extremist content that the company has tried to manage. Telegram has shut down many ISIS chat channels, and continues to do so, and last year it suspended an Iranian channel for encouraging users to join violent protests.