China urged the United States on Thursday to immediately stop all forms of official exchanges with Taiwan ahead of the arrival on the island of US Undersecretary of State for Economic Growth, Energy and the Environment Keith Krach, saying it will take necessary measures as the situation develops.

Krach arrived in Taiwan late Thursday afternoon for a memorial service on Saturday for former Taiwan leader Lee Teng-hui. He was expected to meet Taiwan leader Tsai Ing-wen on Friday. He also was to attend an economic and commercial dialogue with Taiwan authorities, local media reported.

His visit follows a trip last month by US Secretary of Health and Human Services Alex Azar, the highest-level US official to travel to the island in four decades.

Foreign Ministry spokesman Wang Wenbin said China firmly opposes any official exchange between the US and Taiwan, which is a consistent and clear policy.

China lodged stern representations with the US over Krach's trip, which would embolden "Taiwan independence" forces, damage Sino-US ties and harm cross-Straits stability and peace, the spokesman said.

"We urge the US to fully recognize the extreme sensitivity of the Taiwan question," he said, adding that the US should stop expanding relations with the island in any substantive way.

He demanded the US abide by the one-China principle as well as the three Sino-US joint communiques and properly handle Taiwan-related issues.

Speaking of Krach's trip, Ma Xiaoguang, a spokesman for the Taiwan Affairs Office of the State Council, said on Wednesday that the Taiwan question is China's internal affair, and no external forces are allowed to interfere.

"We firmly oppose any form of official exchanges between Taiwan and countries that have established diplomatic relations with China. This kind of behavior interferes with China's internal affairs, hurts the feelings of the Chinese people and violates the norms of international relations," he said.