Beijing (CNN) China has lodged a protest with the US following the official opening of Washington's new de facto embassy in Taiwan, a self-ruled island off China's southeastern coast that Beijing considers a renegade province.

"The United States sending officials to Taiwan under any excuses is in serious violation of the 'one China' principle," Geng Shuang, a Chinese foreign ministry spokesman, said Tuesday. "It interferes with China's internal affairs and negatively impacts China-US relations."

"We urge the US to abide by its pledge to China and correct its mistake to avoid harming China-US relations and peace in the Taiwan Strait."

The American Institute in Taiwan, as the de facto US embassy in Taipei is called, was officially declared open Tuesday morning, in a ceremony attended by senior US diplomats and Taiwan President Tsai Ing-wen.

In an opening address, Assistant US Secretary of State for Educational and Cultural Affairs Marie Royce described the sprawling five-story complex, which cost $255 million to build, as much more than mere bricks and mortar.

(L-R) Taiwanese Foreign Minister Joseph Wu, former Taiwanese President Ma Ying-jeou, chairman of the American Insitute in Taiwan (AIT) James Moriarty, US assistant Secretary of State for Education and Culture Affairs Marie Royce, Taiwanese President Tsai Ing-wen, Overseas Buildings Office Principal Deputy Director Ambassador William Moser and AIT Director Kin Moy pose for a picture during AIT the opening ceremony, Tuesday.

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