The US and Taiwan announced the initiative on Wednesday, which marked the formal start of trade negotiations. Taiwan's trade representative, John Deng, will head to Washington next month for the talks.

Deng said the initiative cover 11 areas, including "trade facilitation, regulatory practices, agriculture, anti-corruption, supporting small and medium-sized enterprises, digital trade, labor rights, the environment, standards, state-owned enterprises, and non-market practices and policies."

The trade talks are the latest example of the US taking steps to boost informal relations with Taiwan. Chinese Foreign Ministry spokesman Zhao Lijian said the US should "stop negotiating agreements with implications of sovereignty and of official nature, and refrain from sending any wrong signal to the 'Taiwan independence' separatist forces."

Zhao also called on the US to stop selling weapons to Taiwan in response to comments from Secretary of Defense Lloyd Austin.

The Pentagon chief said the US "will make available to Taiwan defense articles and services necessary to enable it to maintain a sufficient self-defense capability commensurate with the Chinese threat."

Meanwhile, on Friday China's military has "formally requested a meeting between Defense Secretary Austin and Chinese Defense Minister Wei Fenghe in Singapore next week," according to a senior US defense official.