After revelations that encrypted messaging app Telegram was being used as a promotional and recruitment tool by ISIS, the company has announced that it is taking measures to block access to dozens of public channels used by the group.

"We were disturbed to learn that Telegram's public channels were being used by ISIS to spread their propaganda," a Telegram spokesperson posted in the service's Telegram News channel. "We are carefully reviewing all reports sent to us at and are taking appropriate action to block such channels. As a result, this week alone we blocked 78 ISIS-related channels across 12 languages."

The company added that it will soon be introducing an update to make it easier for people to report any "objectionable content."

Berlin-based Telegram has 60 million active users who use the service as a secure way to send messages and exchange photos, videos, stickers and files of any type up to 1.5 GB in size. It also provides optional end-to-end encrypted messaging with self-destruct timers. It was created two years ago by Pavel Durov, who also founded VK, Russia's largest social network site.

Durov told Mashable that although the company is doing more to regulate public channels, "there are no changes to private chats - privacy is sacred. Technology can be dangerous in the wrong hands, and unfortunately it is true for pretty much every major technological advancement in history"

Telegram did note in an FAQ on its website that while it will pull content that is illegal in certain countries, such as pornography, it does not block freedom of speech, even in areas where it is restricted.

"Please note that this does not apply to local restrictions on freedom of speech. For example, if criticizing the government is illegal in a country, Telegram won't be a part of such politically motivated censorship. This goes against our founders' principles. While we do block terrorist (e.g. ISIS-related) bots and channels, we will not block anybody who peacefully expresses alternative opinions."

While blocking public channels means that ISIS members will no longer be able to spread propaganda or publish links to terrorist sites, the group will still be able to use private groups - which can include up to 200 users - to securely pass information between members. Reiterating Durov's statement, a Telegram spokesperson wrote: "All Telegram chats and group chats are private amongst their participants. We do not process any requests related to them."

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