BEIJING, Sept. 1 (Xinhua) -- A foreign ministry spokesperson on Tuesday urged the United States to abide by the one-China principle, and to cease lifting its substantial relationship with Taiwan as well as any forms of official contact with Taiwan.

Spokesperson Hua Chunying made the comments in response to U.S. Assistant Secretary of State for East Asian and Pacific Affairs David Stilwell's announcement on Monday that the United States was establishing a new bilateral economic dialogue with Taiwan, aiming at strengthening "ties" with Taiwan.

Stressing that the Taiwan question concerns China's core interests, Hua said at a daily press briefing that nobody should underestimate China's firm resolve and determination to safeguard national sovereignty and territorial integrity.

"The one-China principle is the political basis and fundamental precondition for the establishment and development of China-U.S. diplomatic ties," Hua said, adding that there is only one China and Taiwan is an inalienable part of China's territory.

In response to Stilwell's announcement of the declassification of six Reagan-era security assurances given to Taiwan, Hua said the so-called Taiwan Relations Act unilaterally enacted by the United States and the so-called "Six Assurances" to Taiwan constitute gross interference in China's internal affairs.

They severely violate the one-China principle and the three China-U.S. joint communiques, as well as basic norms governing international relations, Hua said, adding that they are entirely wrong, illegal and invalid.

"The Chinese government voiced firm opposition from the very beginning," she said, calling on the United States to abide by the one-China principle and the three China-U.S. joint communiques, rather than the so-called Taiwan Relations Act or "Six Assurances."

"We urge the United States to abide by the one-China principle and the provisions of the three China-U.S. joint communiques, to stop lifting its substantial relationship with Taiwan and to cease any forms of official contact with Taiwan, so as not stray further down an erroneous path," Hua said.