Alongside economic and political ties, Moscow and Beijing have deepened military cooperation in recent years as both countries seek to counterbalance what they see as a United States-led global order.

The drills, named "Joint Sea-2025", were part of regular bilateral cooperation plans and "not directed against third parties", Chinese defence ministry spokesperson Zhang Xiaogang told a press conference Wednesday.

After the drills, they will also conduct naval patrols in "relevant waters of the Pacific", Zhang said.

Last year's "Joint Sea-2024" exercises were held along China's southern coast.

The "Joint Sea-2025" drills are due to take place ahead of a planned visit to China by Russian President Vladimir Putin beginning late August.

Putin will attend a summit of the Shanghai Cooperation Organization as well as celebrations, including a military parade, to mark the 80th anniversary of the end of World War II.

He will also hold talks with Chinese leader Xi Jinping.

Relations between the two countries have deepened since Russia invaded Ukraine in February 2022.

China has never denounced Russia's more than three-year military war nor called for it to withdraw its troops, and many of Ukraine's allies 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.

Xi told Russia's foreign minister earlier in July that their countries should "strengthen mutual support" during a meeting in Beijing.