China's Foreign Ministry has rejected President-elect Donald Trump's suggestion that he might use support of Taiwan as a bargaining chip in future negotiations between the two sides.

Spokesman Lu Kang said Sunday that the "one China" policy is "non-negotiable" and the political foundation of the U.S.-China relationship. Since recognizing Beijing in 1979, Washington has maintained only unofficial ties with Taiwan, the self-governing island that Beijing considers its territory.

But since winning the November election, Trump has said he would consider that policy in a discussion about trade and other issues.

He told The Wall Street Journal in an interview published Friday that "everything is under negotiation, including 'one China.'"

Beijing has repeatedly pushed back against any suggested reconsideration of Taiwan, which it considers a core national interest.