The editor-in-chief of a Russian news outlet designated a "foreign agent" after it investigated the poisoning of opposition politician Alexei Navalny has accused the Russian state of destroying the media.

The Insider and Roman Dobrokhotov (above), its editor-in-chief, angered the Kremlin by helping identify state security officials it said were behind the poisoning of Navalny in August last year.

The Kremlin has denied responsibility for Navalny falling ill and cast...