The People's Liberation Army's Eastern Theatre Command said a naval fleet had taken part in a training to assess its collaborative combat capabilities.

The military did not say exactly when or where the drills took place, or which specific units took part.

The exercises included joint anti-submarine operations, joint search and rescue and damage control, it said in a statement.

They "effectively tested and enhanced the fleet's readiness in actual combat capabilities," the statement said.

Footage released by the theatre command showed Chinese sailors on grey warships rushing to battle stations as alarm bells sounded.

It then showed gun batteries on the ships' decks swivelling and firing shells and missiles into the air in plumes of flame and smoke.

China claims sovereignty over a sweep of disputed islands, reefs and waters in the East and South China seas.

It has ramped up pressure on regional rivals in recent months in what analysts say is a concerted effort to force their compliance.

Beijing claims the self-ruled island of Taiwan, islands in the East China Sea also claimed by Japan, and almost the entire South China Sea -- notably clashing with Philippine and Vietnamese fishers and sailors in the last few months.

World leaders have discussed the territorial disputes at a summit in Laos this week.

US Secretary of State Antony Blinken said Friday that Washington was "concerned about China's increasingly dangerous and unlawful actions on the South and East China Seas".