China has honed its "round-the-clock aerial anti-submarine combat capabilities" in drills in the South China Sea, the military says.
China's military says it has held intensive anti-submarine exercises in the strategically important South China Sea as part of efforts to hone its capabilities amid rising maritime tensions with its neighbours and their allies.
In an undisclosed area in the South China Sea, more than a dozen flights of anti-submarine patrol aircraft operated non-stop for more than 40 hours searching for submarines and simulating attacks, the Southern Command Theatre of China's People's Liberation Army said in a statement on Monday.
"It has effectively honed the military's round-the-clock aerial anti-submarine combat capabilities," the statement said.
The exercise was conducted late at night and in the early morning to accumulate experience at different hours.
The statement did not say whether any non-Chinese submarines were identified in the area.
It was one of several such drills this year and was part of broader activities the Chinese military has conducted in the Indo-Pacific region.
The United States and its allies have also stepped up military activities, especially in the South China Sea, most of which is claimed by Beijing.
Last week, the US and Indonesian defence chiefs said China's territorial claims in the South China Sea were "inconsistent with international law".
The US Navy said China's "aggressive behaviour" in the area, including using water cannons against a Philippine vessel, must be challenged and checked.
The largest of the US Navy's forward-deployed fleets, the Seventh Fleet, headquartered in Japan, operates as many as 70 ships and has about 150 aircraft and more than 27,000 sailors.
The US Navy operates about two dozen nuclear-powered attack subs across the Pacific.
The nuclear submarine capability of US allies in the region will be further enhanced in coming years with the AUKUS agreement between the US, Australia and Britain.
"Japan and the United States have frequent submarine activities in the region," Chinese military commentator Song Zhongping said, adding those activities were not disclosed.