Taiwan's Defence Ministry says it is monitoring “waves of test-firing” by China's missile unit in a region more than 1600km from the self-ruled island and that its air force stepped up its alertness.
China views the democratic island as a breakaway province that should be reunified with the mainland.
According to Taiwan's military news agency, the ministry had detected “multiple waves of test-firing operations” by China's Rocket Force in Inner Mongolia on Saturday.
It did not give details on the tests taken by the force, which takes charge of China's arsenal of missiles.
It is not immediately clear whether the tests were related to China's harassment of Taiwan.
In recent years, China has ramped up its military activities around the island, which is ruled by the Democratic Progressive Party.
In May, Taiwan's newly elected President Lai Ching-te said in his inauguration speech that he wants peace with China and urged it to stop its military threats and intimidation of the island.
China's military has displayed a strong show of force toward Taiwan since Wednesday, when the US new top envoy to Taipei promised that Washington would help the island defend itself.
Taiwan's Defence Ministry said Thursday it had detected 66 warplanes around the island and that dozens flew across the median line in the Taiwan Strait, the de facto boundary between the two sides.
On Saturday, 30 warplanes were also detected around Taiwan over a 24-hour period, with 20 crossing the median line.
The US, like most countries, does not recognise Taiwan.
But it is the island’s main partner and is bound by US laws to provide it with the means to defend itself.
Less than a month ago, the US State Department approved the sale to Taiwan of missiles and drones for an estimated $US360 million ($A533 million).
Meanwhile, Chinese state broadcaster CCTV reported that Russian warships arrived at a port in Zhanjiang city, in Guangdong province, on Friday for joint naval drills.
The military exercise will include anti-missile exercises, sea strikes and air defence, CCTV said.
It is expected to last until around mid-July.
The exercise aims to demonstrate the armies' capabilities in jointly tackling maritime security threats and preserving peace and stability regionally and globally, China's defence ministry said Friday.
It would further deepen the strategic partnership of both sides “for the new era”, it said.
Earlier this week, NATO allies called China a “decisive enabler” of Russia’s war against Ukraine in their most serious rebuke of Beijing.
They also expressed concerns over Beijing’s nuclear arsenal and its capabilities in space.
The sternly worded final communiqué, approved by the 32 NATO members at their summit in Washington, makes clear that China is becoming a focus of the military alliance.
The European and North American members and their partners in the Indo-Pacific increasingly see shared security concerns coming from Russia and its Asian supporters, especially China.
In response, China accused NATO of seeking security at the expense of others and told the alliance not to bring the same “chaos” to Asia.
Its foreign ministry maintained that China has a fair and objective stance on the Ukraine issue.
