Alongside economic and political ties, Moscow and Beijing have strengthened their military cooperation in recent years, and their relations have deepened since Russia invaded Ukraine in February 2022.

The "Joint Sea-2025" exercises kicked off in waters near the Russian port of Vladivostok and would last for three days, China's defence ministry said in a statement on Sunday.

The two sides will hold "submarine rescue, joint anti-submarine, air defence and anti-missile operations, and maritime combat".

Four Chinese vessels, including guided-missile destroyers Shaoxing and Urumqi, are participating in the exercises alongside Russian ships, the ministry said.

After the drills, the two countries will conduct naval patrols in "relevant waters of the Pacific".

China and Russia have carried out annual drills for several years, with the "Joint Sea" exercises beginning in 2012.

Last year's drills were held along China's southern coast.

The Chinese defence ministry said Friday that this year's exercises were aimed at "further deepening the comprehensive strategic partnership" of the two countries.

China has never denounced Russia's more than three-year war nor called for it to withdraw its troops, and many of Ukraine's allies, including the United States, believe that Beijing has provided support to Moscow.

China insists it is a neutral party, regularly calling for an end to the fighting while also accusing Western countries of prolonging the conflict by arming Ukraine.