China claims democratic Taiwan as part of its territory and maintains a near-daily presence of fighter jets, drones and warships around the island, which is 180 kilometres (110 miles) from the southern Chinese coast.

Taiwan is also a crucial part of a chain of islands that military strategists say serve as a gateway from the South China Sea -- which China claims in nearly its entirety -- to the Pacific Ocean.

At around 9:30 am (0130 GMT) Wednesday, Taipei said that "since 0520 today, the Ministry of National Defence detected a total of 37 Chinese aircraft", including fighter jets, bombers and drones.

Thirty-six of the aircraft crossed the sensitive median line of the Taiwan Strait -- which bisects the narrow waterway separating the island from China.

"(The aircraft) headed to the Western Pacific via our southern and southeastern airspace to cooperate with the aircraft carrier the Shandong in conducting 'joint sea and air training'," the defence ministry said in a statement.

Defence Minister Wellington Koo told reporters the Shandong "did not pass through the Bashi Channel", the area off Taiwan's southern tip where Chinese ships typically transit en route to the Pacific Ocean.

Instead, it "went further south through the Balingtang Channel towards the Western Pacific," he said, referring to a waterway just north of the Philippines' Babuyan Island -- about 250 kilometres south of Bashi.

The Chinese flights came a day after Japan's Joint Staff Office said four PLA navy vessels -- including the Shandong -- were sailing 520 kilometres southeast of Miyako Island.

The Shandong "was observed landing and departing fighter aircraft and helicopters on board," it said.

The Philippines' military public affairs chief said they had received reports of a China-Russia exercise taking place in the Philippine Sea, though he did not comment about the Shandong directly.

"We will continue to monitor this situation to ensure (the Philippines') sovereign rights are not violated," Colonel Xerxes Trinidad said Wednesday.

Tensions between Manila and Beijing have ramped up following a series of escalating confrontations over the hotly disputed South China Sea.

- 'China's repeated provocation' -

China has never renounced the use of force to bring Taiwan under its control and has increased military and political pressures on the island in recent years.

In May, days after Taiwanese President Lai Ching-te took office, China launched war games around the island as "punishment" for an inauguration speech that Beijing called a "confession of Taiwan independence".

Beijing's aircraft and vessels have also edged closer to the island, according to Taiwan's defence ministry.

An illustration released Wednesday showed that some of the aircraft came 39 nautical miles off Taiwan's southern tip.

On Wednesday Lai met with Raymond Greene, new director of the American Institute in Taiwan, the de-facto US embassy.

He emphasised their "solid partnership... in the midst of China's repeated provocation and attempts to change the status quo in the Taiwan Strait".

While the United States, like many other countries, does not officially recognise Taiwan diplomatically, it is Taipei's key partner and major provider of weapons -- a point of consternation for Beijing which has repeatedly called on Washington to stop arming the island.

Greene said Washington would continue to "strongly support Taiwan's ability to defend itself".

"We have a long-term and shared interest to maintain the peace and stability in the Taiwan Strait. This is vital to the prosperity of the Indo-Pacific region, as well as to global security," he said.

burs-dhc/mtp