BEIJING China said on Tuesday it had lodged a protest with the United States over a visit by Washington's environmental protection chief to self-ruled Taiwan this week.
Environmental Protection Agency (EPA) administrator Gina McCarthy's visit is the first by a cabinet-level official since 2000, according to Taiwan's presidential office. Taiwan President Ma Ying-jeou met her on Monday.
McCarthy was visiting to highlight environmental cooperation between the United States and partners in the Asia-Pacific region.
China's foreign ministry said the visit to Taiwan, which China considers a rebel province, violated promises Washington had made to Beijing and that China was "resolutely opposed" to it.
"No matter what goal the U.S. EPA administrator has in visiting Taiwan, she has violated ... the promises made by the United States to China on the Taiwan issue," spokeswoman Hua Chunying told a daily news briefing.
"China expresses resolute opposition and strong dissatisfaction with this, and we have launched serious representations to the U.S. side. We urge the U.S. to prudently and appropriately deal with the issue in an effort to avoid doing further damage to the U.S.-China relationship."
China and Taiwan have been ruled separately since defeated Nationalist forces fled to the island at the end of a civil war with the communists in 1949. China has never renounced the use of force to bring Taiwan under its control.
The United States broke formal diplomatic ties with Taiwan in 1979 when it extended recognition to the Chinese government in Beijing, but maintains close unofficial relations with the democratic island.
The United States is also legally bound to come to Taiwan's aid in the event of an attack, under the Taiwan Relations Act.
China's defense ministry earlier this month expressed anger after the U.S. House of Representatives agreed to authorize the sale to Taiwan of four second-hand U.S. warships, saying the United States had ignored Chinese protests.
(Reporting By Megha Rajagopalan; Editing by Nick Macfie)