North Korea possesses significant cyber capabilities and works with all kinds of cyber criminals including those from Russia, US National Security Advisor Jake Sullivan said Tuesday.

The remarks came after President Joe Biden warned of Russian cyber attacks.

"All I can say generally is that North Korea cyber capabilities have been manifest in the world and they work with all kinds of cyber criminals around the world, including Russian cyber criminals," Sullivan said in a press briefing.

Sullivan did not provide any other details, saying "I've got nothing further for you on that today."

Biden on Monday told American businesses to be alert for cyber attacks by Russia.

"And what I want to mention very much, very quickly with you all is one of the tools he's most likely to use, in my view, in our view, is cyber, cyber attacks," the US president said before a business meeting in Washington, adding the Russians have a "very sophisticated cyber capability."

North Korea is said to operate an army of over 7,000 trained hackers, with many of them based in China and Russia. (Yonhap)