Chinese media on Monday warned the US for challenging Beijing's "One China Policy," with a leading daily threatening to take "off the gloves" if Washington used Taiwan as a "bargaining chip".

An editorial in state-run China Daily called Taiwan a "Pandora's box" which had "the lethal potential to upend" Sino-US ties. 

Another newspaper, Global Times, said Beijing would combat "mercilessly" with the backers of Taiwan's independence. 

The hard-hitting articles came in the wake of US President-elect Donald Trump's recent interview to a newspaper in which the former real-estate mogul said America need not consider Taiwan as an integral part of China. 

"Taiwan has been off limits in China-US diplomacy thanks to the understanding that it is a Pandora's box of lethal potential, and that opening it may upend the hard-earned, firmly held fundamentals governing the relationship," China Daily said.

"If Trump is determined to use this gambit on taking office, a period of fierce, damaging interactions will be unavoidable, as Beijing will have no choice but to take off the gloves," the leading daily added.

Taiwan, a self-ruled island, is claimed by China. The US, since 1979, has acceded to the 'One China' policy and refrained from diplomatic ties with Taiwan.

US-China ties have come under severe strain after Trump made incendiary remarks against the second-largest economy of the world. 

Besides Taiwan, Trump has aggressively challenged Beijing's sovereignty over the disputed South China Sea. So much so that US Secretary of State-elect Rex Tillerson threatened to bar China from the islands in the contested waters. 

The paper said China chose not to slam the US when Trump received a phone call from Taiwan President Tsai Ing-wen.

Instead, the Chinese Foreign Minister termed the call a "petty trick" by Taipei, the paper said. 

It said Beijing showed patience even when Trump told a news channel that the US would not "be bound by the One China policy".

"Beijing simply reiterated that acknowledgment of One China is fundamental, and non-negotiable, for healthy ties."

However, the paper said that Trump's reiterating the same point in another newspaper interview cannot be a repeated mistake. 

"To many, that was a mistake Trump made twice."

"Yet when Trump told the Wall Street Journal on Sunday 'everything is under negotiation including one China', reinforcing the impression that he intends to use Taiwan as a bargaining chip, Beijing did not go beyond what it had already said."

"Such a measured response can only come from a genuine, sincere wish that the less-than-desirable, yet by-and-large manageable, big picture of China-US relations will not be derailed before Trump even enters office."

"It would be a blessing for both parties, and indeed for the world, if such goodwill could be appreciated and reciprocated. But that seems unlikely."

"It seems wishful thinking to assume Trump and his team's remarks on Taiwan have been based on bluster or miscalculation. On the contrary, it appears the next administration is intending to use the one-China policy as its trump card."

"It would be good if after his inauguration Trump can demonstrate more statesmanship. But Beijing should not count on his raising the stakes being a pre-inauguration bluff, and instead be prepared for him to continue backing this bet.

"It may be costly. But it will prove a worthy price to pay to make the next US president aware of the special sensitivity, and serious consequences of his Taiwan game."

Another newspaper, Global Times, seconded China Daily's viewpoint. 

"The Chinese mainland will be prompted to speed up Taiwan reunification and mercilessly combat those who advocate Taiwan's independence," it said in an editorial.