BEIJING - China this week staged a large-scale naval and air exercise on its southeast coast, as South Korea and the United States conducted their own naval drill opposed by Beijing, state media said Friday.

The live-fire exercises in the South China Sea on Monday also came three days after US Secretary of State Hillary Clinton said the resolution of disputes in the contentious waters was "pivotal" for regional stability.

A large group of submarines and warships from the People`s Liberation Army Navy fired guided missiles and tested anti-missile air defence systems during the exercise, the official Xinhua news agency said.

Navy aircraft also conducted "air control operations", Xinhua said.

Artillery troops also staged an exercise in China`s east coast this week, earlier reports said.

It was not immediately clear if the two Chinese exercises were pre-planned or came in response to the four-day joint naval and air drill between the United States and South Korea, which ended Wednesday.

The US-South Korean exercise was conducted as a warning to North Korea -- China`s ally -- following the sinking of a South Korean warship blamed by Seoul and its allies on a North Korean submarine.

China is North Korea`s closest ally and trade partner and has refused to join international condemnation of Pyongyang for the incident.

Beijing had expressed concern over the July 25-28 drill, which was initially supposed to be held in the Yellow Sea separating China and the Korean peninsula but was later relocated to the Sea of Japan following Beijing`s protests.

It has warned against further actions that it says could raise tensions in the region.

Last week, Clinton told an Asia-Pacific security forum in Vietnam that the United States had an interest in "freedom of navigation, open access to Asia`s maritime commons, and respect for international law in the South China Sea."

"We oppose the use or threat of force by any claimant," she said.

Beijing`s territorial claims over potentially resource-rich archipelagos in the South China Sea conflict with those of some members of the Association of Southeast Asian Nations (ASEAN).

US commanders have made it clear they are watching China`s military buildup, particularly its naval reach into the South China Sea.

BDST: 12:08 HRS, July 30, 2010