Secure and encrypted messaging app Telegram was temporarily pulled out of Apple's App Store.

Telegram has risen in popularity thanks to its focus on security features and the ability to hold secret conversations with end-to-end encryption with no trace on its servers, having the ability to block forwarding, supporting self-destructing messages and more.

While Most rival messaging services do support end-to-end encryption, but that wasn’t the case when Telegram was first introduced back 2013.

When the Telegram app and Telegram X disappeared, CEO Pavel Durov tweeted that the issue was because of "inappropriate content."

Durov who also founded Russia’s largest social network VKontakte, created Telegram “to build a means of communication that can’t be accessed by the Russian security agencies.”

But due to its secretive nature, Telegram has been widely criticized by governments around the world for becoming the messaging “app of choice” for terrorists.

When Telegram and Telegram X were temporarily removed from Apple's App Store, they remained available on Google Play.

According to iOS guidelines, “Apps with user-generated content or services that end up being used primarily for pornographic content, objectification of real people (e.g. “hot-or-not” voting), making physical threats, or bullying do not belong on the App Store and may be removed without notice."

UK Prime Minister Theresa May said in a speech that "smaller platforms can quickly become home to criminals and terrorists. We have seen that happen with Telegram. And we need to see more co-operation from smaller platforms like this."

Previously, Telegram was forced to create a team of moderators in Indonesia to remove “terrorist-related content” after the Indonesian government threatened to ban the messaging app.

Defending itself, Telegram explained that "While we do block terrorist (e.g. ISIS-related) bots and channels, we will not block anybody who peacefully expresses alternative opinions."

Before being removed, Telegram has just launched Telegram X which was at the time at a testing phase on iOS.

Telegram X is meant to be a faster alternative to the original Telegram app, which includes a refreshed UX with a cleaner look, smoother animations, swiping actions for shortcuts, themes and more efficient battery use.

The company describes the rebuilt and redesigned app as "experimental", explaining that it "may or may not eventually replace the existing official app."

“But even if it doesn’t, it will speed up the development of Telegram by allowing us to quickly test new approaches and technologies," it added.

Given that Telegram X is a sizable ambition, it's said to be the groundwork for future projects, like the ICO plan Durov has previously announced. Here, Telegram quietly creates the foundation where its platform can support blockchain technology.