Chinese warplanes and naval ships crossed the median line of the Taiwan Strait following a high-profile visit by U.S. House Speaker Nancy Pelosi to the self-ruled island, Taiwan's defense ministry said Friday.

The ministry said in a statement that since the Chinese People's Liberation Army started four days of live-fire drills in six areas surrounding Taiwan on Thursday, Chinese warplanes and naval ships have been detected crossing the median line of the Taiwan Strait.

It is rare for a Chinese warship to cross the line and the latest development highlights intensifying cross-strait tensions following China firing 11 ballistic missiles near Taiwan on Thursday.

Photo posted by the Chinese military's Eastern Theater Command on social media platform Weibo on Aug. 3, 2022, shows a military exercise in progress. (Kyodo)

Around 10 Chinese navy ships and about 20 Chinese military aircraft crossed the median line, Reuters reported, citing a Taiwan source briefed on the matter.

China could use the large-scale drills as an opportunity to make the median line a dead letter, defense experts say.

Be it firing ballistic missiles or crossing the median line of the Taiwan Strait, the ministry said the military exercises are "highly provocative."

The median line divides the 180-kilometer-wide body of water that separates Taiwan and the southeast coast of mainland China.

China began the drills one day after Pelosi concluded her highly-controversial trip to Taiwan on Wednesday, a visit she made despite strong opposition from China.

The ministry said China fired 11 Dongfeng ballistic missiles near Taiwan over two hours on Thursday, the largest missile test in decades in waters around the island. The Japanese government said five of the missiles landed within its exclusive economic zone.

In Japan, the local fishermen's cooperative of Yonaguni Island, Okinawa Prefecture, located about 110 kilometers from Taiwan, on Friday requested members refrain from operating until the Chinese military exercises are over and safety is assured.

"I want to emphasize that we will neither escalate conflict nor instigate disputes," Taiwan President Tsai Ing-wen said Thursday in a video released by her office. "But we will resolutely defend (our) sovereignty and security as a bulwark of democracy and freedom."

Chinese drones have also flown above the area of Taiwan's Kinmen Islands off the coast of Xiamen, China, since Wednesday, the ministry said, adding that flares were fired to drive them away.

The websites of Tsai's office and other government agencies such as the Defense Ministry and Foreign Ministry have come under foreign cyberattack. There has been speculation China and Russia are behind the attacks.

China has also suspended imports of agricultural products from Taiwan and stopped exports of natural sands to the island.

Taiwan and China have been governed separately since they split in 1949 due to a civil war. Beijing regards the island as a renegade province to be reunified with the mainland, by force if necessary.

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