China warned the US government on Wednesday against top US officials meeting Taiwan's Mainland Affairs Minister who is on a visit to Washington.
Taiwan's Chen Ming-tong began his visit to the US capital on Monday and was set to speak at a think tank seminar and meet academicians as well as hold meetings with government officials, according to the Taiwanese government.
"We firmly oppose any formal ties between the US and Taiwan," Chinese Foreign Ministry spokesperson Hua Chunying was quoted as saying by Efe news.
"We hope the US can properly handle Taiwan related issues, take concrete actions to uphold the overall picture of China-US relations," Hua further warned Washington.
The Donald Trump administration reached out to Taiwan after a telephone conversation in 2016 with President Tsai Ing-wen, by selling arms to the island and approving a law that did away with restrictions on official visits between the US and Taiwan.
Last month, Washington inaugurated a new de-facto Embassy in Taipei -- officially called the American Institute in Taiwan -- as the US does not maintain official diplomatic ties with Taiwan. The mission has more than 500 employees.
The US State Department had requested the Pentagon to assign Marines for the security of the building, a move opposed by Beijing.
China, which maintains that Taiwan is a rebellious island since the end of the 1949 civil war, demands that countries should not maintain diplomatic relations with Taiwan, under its "One China Principle".