Three Russian admirals have been dismissed over the Kursk disaster.
Several top navy officials have also been reprimanded by President Vladimir Putin.
The disciplinary action was announced after President Putin was briefed on the Kursk inquiry.
Admiral Vyacheslav Popov, the commander of the Northern Fleet, and Admiral Mikhail Motsak, the Northern Fleet's chief of staff, were both demoted, according to the Interfax news agency.
It is not immediately clear whether their ranks will also be reduced.
Russia's naval Commander-in-Chief Vladimir Kuroyedov said that "another group of admirals and officers from the Northern Fleet" were reprimanded and will face disciplinary action.
The three admirals who were dismissed were not immediately identified.
Officials did not say explicitly that the action was taken in connection with the Kursk, Russia's nuclear submarine that sank last year during military exercises in the Barents Sea, killing all 118 men aboard.
However, the announcement came almost immediately after Russian Prosecutor General Vladimir Ustinov briefed President Vladimir Putin on the preliminary investigation into the Kursk disaster.
Putin criticised the navy's preparations for the military exercises, which the Kursk was participating in when the disaster struck.