Russian President Vladimir Putin says his country has conducted successful testing of a nuclear-powered cruise missile, in an apparent warning to Western nations.

Putin was speaking at an annual meeting of the Valdai Discussion Club in the southern Russian city of Sochi on Thursday.

Putin said the country has almost completed work on advanced strategic weapons he announced several years ago. He said, "We conducted the last successful test of the Burevestnik nuclear-powered global-range cruise missile." The missile is capable of carrying nuclear warheads.

The president also commented on Russia-Japan relations, which have deteriorated after Russia's invasion of Ukraine.

Putin said, "It is not Russia that imposed sanctions on Japan or closed its window to the country. Japan did that."

Putin went on to say, "If the Japanese side takes some kind of initiative to resume dialogue, it would be good." He added he is prepared to hold talks if Japan was willing.

Putin also spoke about the plane crash in August that killed former Wagner mercenary leader Yevgeny Prigozhin. He said, "Fragments of hand grenades were found in the bodies of those killed in the crash." He added, "There was no external impact on the plane."

Putin said, "This is an established fact," saying the investigative committee reported to him a few days ago.

The committee has not yet issued a public report on the cause, and Putin did not provide further details.