Taiwan has accused China, which regards the self-ruled island as a breakaway province, of kidnapping eight of its nationals who it said had been acquitted in a cybercrime case in Kenya.
Kenya's attorney-general said in January it was considering a request from Beijing to extradite 76 Chinese charged with cybercrime in Kenya for trial in their homeland.
But Taiwan said some of those people were from Taiwan and that 23 of its people had been acquitted last Tuesday by a Kenyan court and given 21 days to leave.
Yet China pressured Kenyan police to put eight of the Taiwanese nationals on a Chinese jet bound for China on Friday, Taiwan's Foreign Ministry said. It did not say how they were taken.
"This is an uncivilised act of illegal kidnapping and a serious violation of basic human rights," the ministry said on Monday, adding it was demanding the immediate return of the eight.
Taiwan's ruling Democratic Progressive Party, which distrusts China, has also demanded China "repatriate our people and guarantee their legal rights".
China views Taiwan as a wayward province, to be brought under Beijing's control, by force if necessary. Defeated nationalist forces fled to the island in 1949 after a civil war with the communists in control in Beijing.
Only 22 countries recognise Taiwan, with most, including Kenya, having diplomatic relations with Beijing, recognising its "one China" policy.
Taiwan had sent officials from its representative office in South Africa to Kenya to try to deal with the case as it had no office in Kenya, the Foreign Ministry added.
China's Taiwan Affairs Office, which oversees relations with Taiwan, did not respond to a request for comment, and neither did China's Ministry of Public Security.
Kenyan government officials were not immediately available for comment.
China has looked on with suspicion at Taiwan since Tsai Ing-wen and her independence-leaning DPP won presidential and parliamentary elections in January.
