Russia Today reports:

A self-made explosive device has been defused at another St Petersburg Metro station -- Ploshchad Vosstaniya, Russia's National Anti-Terrorism Committee said.

Moscow Mayor Sergey Sobyanin has ordered security to be stepped up in the Moscow Metro, the Moscow Central Ring and intercity trains, the Moscow Transport service tweeted.

Three trains of the Moscow Central Ring have been evacuated after an unidentified object was located.