North Korean leader Kim Jong Un sent a message of sympathy to Russian President Vladimir Putin over the massacre at a Moscow concert hall, KCNA state news agency said.

Kim "expressed deep condolences and sympathy" to Putin and to the Russian people, the victims and their families on the news of heavy casualties caused by "a large-scale terrorist attack in (the) Moscow region," KCNA said.

The message also said "nothing can justify the heinous terrorism threatening human life."

The ties between Moscow and Pyongyang grew in recent months following the North Korean leader's visit to Russia's far east last year and Pyongyang's weapons aid for Moscow in its war with Ukraine.