The military exercises, which coincide with US President Joe Biden's first Asia trip as president, will continue through Monday, according to Chinese officials.
China is holding military exercises in the disputed South China Sea coinciding with US President Joe Biden’s visits to South Korea and Japan that are largely focused on countering the perceived threat from Beijing.
The Maritime Safety Administration office in the southern island province of Hainan said on Friday that the drills began on Thursday and would continue through Monday.
It said other craft would be prohibited from entering the area but gave no further details.
China claims the South China Sea virtually in its entirety and the crucial waterway has become a potential flashpoint for conflict in Asia.
The US does not take a foreign position on the sovereignty issue but insists on the right to operate freely in the sea and frequently sails warships close to militarised Chinese-held islands in the area in what are termed “freedom of navigation operations."
China routinely protests such missions, labeling them deliberate provocations that endanger peace and stability. To assert its claim, it has built airstrips and other military infrastructure atop human-made islands built on coral reefs and atolls.
Brunei, Malaysia, the Philippines and Taiwan also exercise overlapping claims in the South China Sea.
'Anti-China rhetoric kicking up dust'
Since the beginning of the month China's first aircraft carrier, the Liaoning, has been conducting a mission in the Sea of Japan, described by the Defence Ministry as “routine training" aimed at boosting performance that is “in-line with relevant international law and international practice, and not targeting any party."
China also flew a pair of long-range nuclear-capable H-6 bombers through the area on Wednesday, Chinese media reports said.
While in Japan, Biden will meet on Tuesday with fellow leaders of the Indo-Pacific strategic alliance known as the Quad, a group that includes Australia, India and Japan.
The four nations share concerns over China's growing regional assertiveness and increasingly capable armed forces.
China views the grouping as a part of a US-led push to impede its economic and political rise and frustrate its attempts to intimidate self-governing Taiwan into accepting its demand to accept Beijing rule.
On Wednesday, Chinese Foreign Minister Wang Yi criticised what he called negative moves by Washington and Tokyo against Beijing during a video call with Japanese Foreign Minister Yoshimasa Hayashi.
“What arouses attention and vigilance is the fact that, even before the American leader has set out for the meeting, the so-called joint Japan-US anti-China rhetoric is already kicking up dust,” Wang said, according to China’s Foreign Ministry.