The Kremlin says Russian television accidentally displayed secret plans detailing a nuclear torpedo system during a presidential photo opportunity.

Two Kremlin-controlled channels, NTV and Channel One, showed a military official looking at a confidential document containing drawings and details of a weapons system called Status-6, designed by Rubin — a nuclear submarine construction company based in St Petersburg.

The nuclear torpedoes, to be fired by submarines, would create "zones of extensive radioactive contamination making them unsuitable for military or economic activity for a long period", said the document, which was clearly visible in the footage for several seconds.

The images were filmed during a meeting between president Vladimir Putin and military officials in the Black Sea city of Sochi on Monday.

The footage aired and was later deleted by the channels, but several websites still published screenshots from it.

"It's true some secret data got into the shot, therefore it was subsequently deleted," Mr Putin's spokesman Dmitry Peskov told journalists.

"In future we will undoubtedly take preventive measures so this does not happen again."

It remained unclear how the images ended up being broadcast on the tightly-controlled channels.

Other documents were blurred or out of focus in the television reports.

The document was shown at a meeting where Mr Putin warned that "Russia will take necessary retaliatory measures to strengthen the potential of our strategic nuclear forces".

AFP