Video released by Russian state news agency TASS showed nine large vessels sailing in a diamond formation as crew members stood to attention on deck.

The drills also included practising the "replenishment of fuel reserves by ships and the transfer of cargo on the go", the defence ministry said, adding that the joint detachment of ships had covered more than 6,400 nautical miles since the start of the exercises.

"A detachment of ships of the Russian Navy and the PLA Navy is currently operating in the waters of the East China Sea," said the ministry, referring to China's People's Liberation Army.

"During this period, the sailors of the two countries conducted anti-submarine exercises, repulsed an air strike by a mock enemy, conducted rescue training at sea, and perfected the skills of taking off and landing helicopters on the decks of warships," the statement read.

Ties between Moscow and Beijing have grown closer in recent years, as prolonged fighting in Ukraine has shattered Russia's relationship with Western governments.

A Chinese defence ministry spokesperson said Monday that naval fleets of the two countries were conducting maritime patrols in western and northern regions of the Pacific Ocean.

"These actions are not aimed at a third party and are not related to the current international and regional situation," the spokesperson added.

Chinese Defence Minister Li Shangfu visited Russia this week to attend the 11th Moscow Conference on International Security, where he called for closer military cooperation.

Moscow and Beijing have ramped up bilateral defence collaboration in recent months, carrying out a joint air patrol over the Sea of Japan and the East China Sea in July.

The displays of force have caused concerns in the region -- the July air patrol led to South Korea deploying fighter jets as a precaution.

burs/je/leg