China's foreign minister has said he hopes Beijing's relations with the US would not be "interfered with or damaged" after president-elect Donald Trump broke with decades-long diplomatic tradition and spoke directly with Taiwan's leader.
Wang Yi dismissed the call between Taiwan's president Tsai Ing-wen and Mr Trump as "just a small trick by Taiwan" that he believed would not change US policy towards China, according to Hong Kong's Phoenix TV.
"The one-China policy is the cornerstone of the healthy development of China-US relations and we hope this political foundation will not be interfered with or damaged," Mr Wang said.
Washington has pursued a so-called "one China" policy since 1979, when it shifted diplomatic recognition of China from the government in Taiwan to the communist government on the mainland.
Under that policy, the US recognises Beijing as representing China, but retains unofficial ties with Taiwan.
Mr Trump's transition team said of the conversation: "During the discussion, they noted the close economic, political, and security ties between Taiwan and the United States. President-elect Trump also congratulated President Tsai on becoming president of Taiwan earlier this year."
Mr Trump tweeted later: "The President of Taiwan CALLED ME today to wish me congratulations on winning the Presidency. Thank you!"
The Taiwanese presidential office said the leaders discussed issues affecting Asia and the future of US relations with Taiwan.
"The (Taiwanese) president is looking forward to strengthening bilateral interactions and contacts as well as setting up closer co-operative relations," it said.
"The president also told US President-elect Trump that she hopes the US will continue to support Taiwan's efforts in having more opportunities to participate in and contribute to international affairs in the future."
It added that the two also "shared ideas and concepts" on "promoting domestic economic development and strengthening national defence" to improve the lives of ordinary people.
Taiwan's presidential office spokesman Alex Huang said separately that Taiwan's relations with China and "healthy" Taiwan-US relations can proceed in parallel. "There is no conflict (in that)," he said.
The White House learned of the conversation after it had taken place, said a senior Obama administration official.
Friday's call is the starkest example yet of how Mr Trump has flouted diplomatic conventions since he won the November 8 election. He has apparently undertaken calls with foreign leaders without guidance customarily lent by the State Department, which oversees US diplomacy.
Ms Tsai was democratically elected in January and took office in May. The traditional independence-leaning policies of her party have strained relations with Beijing.
Over the decades, the status of Taiwan has been one of the most sensitive issues in US-China relations. China regards Taiwan as part of its territory to be retaken by force, if necessary, if it seeks independence. It would regard any recognition of a Taiwanese leader as a head of state as unacceptable.
Taiwan split from the Chinese mainland amid civil war in 1949. The US policy acknowledges the Chinese view over sovereignty, but considers Taiwan's status as unsettled.
Although the US does not have formal diplomatic ties with Taiwan, it has close unofficial ties. Taiwan's government has a representative office in Washington and other US cities. The US also has legal commitments to help Taiwan maintain the ability to defend itself.
Taiwan is separated from China by the 110-mile-wide Taiwan Strait. The island counts the US as its most important security partner and source of arms, but it is increasingly outgunned by China.
Ned Price, a spokesman for the White House National Security Council, said Mr Trump's conversation did not signal any change to long-standing US policy on "cross-strait" issues.
"We remain firmly committed to our 'one China' policy," Mr Price said. "Our fundamental interest is in peaceful and stable cross-strait relations."
The NSC stressed that every president has benefited from the "expertise and counsel" of the State Department on matters like this, which suggested that the White House was frustrated by Mr Trump's conversation with the Taiwanese leader.
Still, the White House said Barack Obama remains committed to a smooth transition to the new administration.
Diplomatic protocol dictates that Taiwanese presidents can travel through the US, but not visit Washington.
Douglas Paal, who served as head of the American Institute in Taiwan during the George W Bush administration, said that to his knowledge the call was unprecedented.