China claims democratic Taiwan as part of its territory and has said it will never renounce the use of force to bring it under Beijing's control.

Taiwan's defence ministry said 28 of the Chinese aircraft had crossed the median line, referring to a line bisecting the Taiwan Strait that separates the island from China.

The military deployed planes and ships in response, a ministry statement said.

The latest report comes during visits by United States congressional delegations, the first since the inauguration of President Lai Ching-te on May 20.

Days later Chinese warships and fighter jets encircled Taiwan in drills that Beijing said were a test of its ability to seize the island.

During the two-day exercise, China vowed that "independence forces" would be left "with their heads broken and blood flowing".

Beijing has in recent years upped military pressure on Taiwan, maintaining a near-daily presence of warplanes, drones and naval vessels around the island.

Experts say these are "grey zone tactics", which stop short of outright acts of war but serve to exhaust Taipei's military.

China said Lai's inaugural speech amounted to calls for independence, "pushing our compatriots in Taiwan into a perilous situation of war and danger".