Screenshot by Lori Grunin/CNET

Secure messaging service Telegram has lost an important round in its fight against the demands of the Russian Federal Security Service (FSB) to turn over all its encryption keys so that it can more easily monitor communications. According to a Bloomberg report, the Russian Supreme court ruled against Telegram Messenger in a legal dispute that's been going on since late December 2017.

According to the report, Telegram plans to appeal. But one ramification of it standing its ground is getting blocked in Russia altogether. Pavel Durov, Telegram founder, commented on Twitter:

Threats to block Telegram unless it gives up private data of its users won't bear fruit. Telegram will stand for freedom and privacy. — Pavel Durov (@durov) March 20, 2018

The company is no stranger to bans, however. One of the most recent was by Iran at the end of December. According to the story, the government's case centered on encryption keys not being considered private data, and that to actually access a specific account it would still need a court order.

We reached out to Telegram Messenger and the Russian government for comment but did not immediately hear back.