In a statement posted on the Telegram messenger app, the Investigative Committee, which probes serious crimes, said that Roman Popkov, a Ukraine-based Russian journalist who was previously a leader of Russia’s banned ultranationalist National Bolshevik Party, was wanted on terrorism and explosives charges.

Tatarsky, a native of eastern Ukraine’s Donbas whose real name was Maxim Fomin, had been addressing an event in the cafe when the blast occurred. Russian officials later said a bomb had been hidden inside a statuette given to him as a gift during the event.

Russian officials have previously named Russian citizen Darya Trepova and Ukrainian national Yury Denisov as suspects in the killing.

In its statement, the Investigative Committee said Popkov had exchanged messages with Trepova over social media and had given her “instructions regarding the preparation of the terrorist act”.

Trepova, an anti-war and feminist activist, was arrested on April 3, while Denisov is believed to be still in Ukraine. Trepova is accused of giving Tatarsky the explosive statuette and has been charged with terrorist offences.

A Moscow court today ordered that Trepova’s pre-trial detention be extended until Sept 2, state-owned news agency TASS reported.

Trepova’s husband told independent Russian media outlets he believed she was framed in the case and had not known the statuette she had been told to deliver contained explosives.