On Thursday at his keynote national day speech, Lai said the People's Republic of China had no right to represent Taiwan, but that the island was willing to work with Beijing to combat challenges like climate change, striking both a firm and conciliatory tone, drawing anger from China.

China is weighing additional trade measures against Taiwan after the Ministry of Commerce said on Saturday it would consider further steps against the self-ruled island. The announcement comes two days after Beijing slammed a speech made by Taiwan President Lai Ching-Te during the island's national day ceremonies.

Taiwan's Mainland Affairs Council, in a statement to Reuters on Thursday, said the four employees had been detained in China's Zhengzhou, home to a major Foxconn plant assembling Apple's iPhones, on suspicion of the equivalent of "breach of trust".

Four employees of the Taiwanese contract manufacturer that makes the Apple iPhone are in detention in China, Taiwanese authorities said Friday.

The employees were detained by public security in the city of Zhengzhou for the equivalent of 'breach of trust' under Taiwan law, Taipei's top China policy body, the Mainland Affairs Council, said