Russian President Vladimir Putin's top security adviser Sergei Shoigu has arrived in North Korea and plans to meet its leader Kim Jong-un, the Tass news agency reported on Friday, his latest visit amid dramatic advances in security ties between the countries.

The Tass report did not have further details and North Korea's state media have not reported on Shoigu's arrival.

Shoigu, former defence minister until May last year, had earlier made visits to Pyongyang as North Korea geared up to deploy troops to fight for Russia in its war against Ukraine.

US and South Korean officials have said North Korea has deployed more than 10,000 troops who were sent into combat in Russia's eastern Kursk region and also shipped heavy weapons including artillery and ballistic missiles.

North Korea is believed to have received military and civilian technology and economic assistance from Moscow in return.

Neither Pyongyang nor Moscow has acknowledged Pyongyang's deployment of troops and weapons, but said they had continued to implement a strategic partnership treaty signed by the countries' leaders in June last year that includes a mutual defence pact. (Reuters)