A top Russian court has upheld the Federal Security Service’s (FSB) right to demand encryption keys from Telegram, dealing the embattled messaging app another blow in its privacy battle with law enforcement.

The FSB has sought tools to break the app’s message encryption and unscramble private conversations since two suspects were accused of using the platform to coordinate the St. Petersburg metro bombings in April 2017. Telegram maintains that it has no access to users’ encryption keys and says the FSB’s demands are unconstitutional.

The Supreme Court ruled on Thursday that the keys to decode encrypted messages don’t fall under the private correspondence protections of the Russian constitution, the Kommersant business daily reported.

The ruling leaves intact the court’s decision on March 20, 2018 that the FSB can legally demand access to user’s encryption keys, Interfax reported.

The dispute will now move to the European Court of Human Rights, where Telegram has registered a complaint, the platform’s lawyer Ramil Akhmetgaliyev told Kommersant.