China rebukes Trump, warns him of 'crushing his own toes' on Taiwan

China offered its sternest rebuke yet to Donald Trump, saying anyone who challenges Beijing's interests in Taiwan will "lift a rock only to crush his own toes".

"If he tries to sabotage the One China policy or harm China's core interests, ultimately he will lift a rocow confident enough to arm-wrestle with Trump," it said.

Trump shocked the diplomatic establishment and angered Beijing by speaking directly with Taiwan's leader Tsai Ing-wen after his election victory.

After fierce criticism of the move, he upped the ante, taking to Twitter to ask why he should not be allowed to speak to Tsai, then attacking Chinese foreign and economic policy.

On Sunday, he went a step further, saying he did not see why Washington must "be bound by a One China policy unless we make a deal with China having to do with other things, including trade."

The remarks were a step too far for Beijing, which had initially seemed resigned to taking a wait-and-see approach to the president-elect.

Trump's comments also earned a rare rebuke from the White House, with spokesman Josh Earnest warning the president-elect that Taiwan is not a "bargaining chip".