CHINA has sent more warplanes towards Taiwan for the second day as the island's leader, senior government officials and a US envoy paid tribute to former president Lee Teng-hui.

Keith Krach, the US under-secretary for state, kept a low profile at the service honouring the man who led Taiwan's transition to democracy.

Krach's presence at the event and on the island has drawn a strong rebuke from China, which sent 18 warplanes across the mid-line of the Taiwan Strait on Friday in an unusually large display of force.

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On Saturday, Beijing dispatched 19 more warplanes, two of which were bombers, according to Taiwan's defence ministry.

The island's air force scrambled its own planes and deployed an air defence missile system to monitor China's activities, according to

a statement.

The service was held at the Aletheia University in Taipei on Saturday morning, with president Tsai Ing-wen honouring Lee for bringing a peaceful political transition to the island democracy.

Lee had built a separate Taiwanese political identity, distinct from mainland China, which claims Taiwan as part of its own territory to be reunited by force if necessary.

His carving out of a non-Chinese identity and insistence that the island be treated as an equal country brought him into direct conflict with Beijing. He died on July 30 at age 97.

Tsai said: "We have a responsibility to continue his endeavours, allowing the will of the people to reshape Taiwan, further defining Taiwan's identity and deepening and bolstering democracy and freedom."

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Former Japanese prime minister Shinzo Abe and the Dalai Lama also paid tribute from afar.

"We Buddhists believe in life after life, so most probably he will be reborn in Taiwan," the Dalai Lama said in a video message. "His rebirth will carry his spirit continuously."

Lee, an agricultural economist and politician, devoted his career toward building democracy on the island through direct elections and other changes.

He was the first government official to speak out and formally apologise for the so-called 228 incident, named after an incident on February 28, 1947, when soldiers under the Kuomintang, or the sole ruling Nationalist Party, shot and killed thousands of civilians in an anti-government uprising.