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Sept 15 (Reuters) - The Russian and Chinese navies are holding joint patrols in the Pacific Ocean, the Russian defence ministry said on Thursday, deepening military and diplomatic ties between Moscow and Beijing when their relations with the West have soured.

A ministry statement on Telegram said crews from both sides were conducting joint tactical maneuvers and carrying out exercises involving artillery and helicopters.

"The tasks of the patrols involve the strengthening of naval cooperation between Russia and China, upholding peace and stability in the Asia-Pacific region, coastal monitoring and safeguarding Russian and Chinese nautical economic sites," it said.

China's President Xi Jinping is due on Thursday to meet Russia's President Vladimir Putin in Uzbekistan to discuss Ukraine and Taiwan, among others, in what is the Chinese president's first trip abroad in more than two years.

The deepening "no limits" partnership between the rising superpower of China and the natural resources titan of Russia is a geopolitical development the West is watching with anxiety.

Russia and China warships conducted their first joint patrols of the western Pacific Ocean in October last year, a move closely monitor by Japan who called the maneuvers as "unusual."

(Reporting by Ronald Popeski in Winnipeg and Lidia Kelly in Melbourne; Editing by Jacqueline Wong and Michael Perry)