Taiwanese President Tsai Ing-wen delivers a speech after her inauguration ceremony in Taipei, Taiwan. AP

Taiwan cannot accept becoming part of China under its "one country, two systems" offer of autonomy, President Tsai Ing-wen said on Wednesday, in a strong rejection of China's sovereignty claim, but called for talks so that both sides could coexist.

In a speech after being sworn in for her second and final term in office, Tsai said relations between Taiwan and China had reached an historical turning point.

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"Both sides have a duty to find a way to coexist over the long term and prevent the intensification of antagonism and differences," she said.

Tsai and her Democratic Progressive Party won January's presidential and parliamentary elections by a landslide, vowing to stand up to China, which claims Taiwan as its own and says it would be brought under Beijing's control by force if needed.

Taiwanese President Tsai Ing-wen (centre) walks to attend an inauguration ceremony in Taipei, Taiwan, on Wednesday. AP

"Here, I want to reiterate the words 'peace, parity, democracy, and dialogue'. We will not accept the Beijing authorities' use of 'one country, two systems' to downgrade Taiwan and undermine the cross-strait status quo. We stand fast by this principle," Tsai said.

China uses the "one country, two systems" policy, which is supposed to guarantee a high degree of autonomy, to run the former British colony of Hong Kong, which returned to Chinese rule in 1997. It has offered it to Taiwan, though all major Taiwanese parties have rejected it.

China's Taiwan Affairs Office, responding to Tsai, said Beijing would stick to "one country, two systems" - a central tenet of Chinese President Xi Jinping's Taiwan policy - and "not leave any space for Taiwan independence separatist activities".

"Reunification is a historical inevitability of the great rejuvenation of the Chinese nation," it said. "We have the firm will, full confidence, and sufficient ability to defend national sovereignty and territorial integrity."

China views Tsai as a separatist bent on formal independence for Taiwan. Tsai says Taiwan is an independent state called the Republic of China, its official name, and does not want to be part of the People's Republic of China governed by Beijing.

Meanwhile, a spokesman at the mainland's top Taiwan body said on Wednesday that, Beijing will "never tolerate" Taiwan's separation from China, after President Tsai Ing-wen was inaugurated for a second term.

China considers the democratic, self-governing island as part of its territory, and has repeatedly advocated for its eventual reunification with the mainland -- using military force if necessary.

Ma Xiaoguang, spokesman for the Taiwan Affairs Office, said China had "sufficient ability to defend national sovereignty and territorial integrity", according to official state news agency Xinhua.

Agencies