China's defence ministry said on Wednesday it's participation in the joint exercises was "unrelated to the current international and regional situation".

Last month, Moscow announced plans to hold "Vostok" (East) exercises from August 30 to September 5, even as it wages a costly war in Ukraine. It said at the time that some foreign forces would participate, without naming them.

China's defence ministry said its participation in the exercises was part of an ongoing bilateral annual cooperation agreement with Russia.

"The aim is to deepen practical and friendly cooperation with the armies of participating countries, enhance the level of strategic collaboration among the participating parties, and strengthen the ability to respond to various security threats," the statement said.

Under Chinese President Xi Jinping and his Russian counterpart Vladimir Putin, Beijing and Moscow have grown increasingly close.

A year ago this month, Russia and China held joint military exercises in north-central China involving more than 10,000 troops. Russian Defence Minister Sergei Shoigu praised the Sibu/Cooperation-2021 drills in China's Ningxia and suggested they could be developed further.

In October, Russia and China held joint naval drills in the Sea of Japan. Days later, Russian and Chinese warships held their first joint patrols in the western Pacific.

The next month, South Korea's military said it had scrambled fighter jets after two Chinese and seven Russian warplanes intruded into its air defence identification zone during what Beijing called regular training.

Shortly before Russia's February 24 invasion of Ukraine, Beijing and Moscow announced a "no limits" partnership, although US officials say they have not seen China evade US-led sanctions on Russia or provide it with military equipment.

Russia's eastern military district includes part of Siberia and has its headquarters in Khabarovsk, near the Chinese border.

Australian Associated Press