Russian President Vladimir Putin warned world powers against using nuclear weapons, saying that no one in their right mind would use them against Moscow.

In response to a question, Putin said he was not ready to declare whether or not Russia needed to resume nuclear weapons testing, saying that "theoretically we could revoke ratification" of the international nuclear test ban treaty.

In a keynote annual speech at the Valdai Discussion Club in Sochi on Thursday, he said Russia had almost completed work on its nuclear-capable Sarmat intercontinental ballistic missile system and successfully tested the nuclear-powered nuclear-capable Burevestnik strategic cruise missile.

He warned that no enemy stands a chance to survive if Russia launches a retaliatory nuclear strike as its potential is incomparably greater.

Putin said the Russian military doctrine provides two reasons for the use of nuclear weapons: as a response to a missile launched on Russian territory and if the existence of the state is threatened.

"To date, there will be no chance for the aggressor to survive in the event of our response ... I don't see the need to change that. No sane person would think of using nuclear weapons against Russia," he said.