China lodged a diplomatic protest on Saturday after US President-elect Donald Trump spoke over phone with President Tsai Ing-wen of Taiwan, but blamed the self-ruled island Beijing claims as its own for the "petty" move.
China's Foreign Ministry said it had lodged "stern representations" with what it called the "relevant US side", urging the careful handling of the Taiwan issue to avoid any unnecessary disturbances in ties. "The one China principle is the political basis of the China-US relationship," it said.
The wording implied the protest had gone to the Trump camp, but the ministry provided no explanation.
Speaking earlier, hours after Friday's telephone call, Chinese Foreign Minister Wang Yi pointedly blamed Taiwan for the exchange, rather than Trump, a billionaire businessman with little foreign policy experience.
US President-elect Donald Trump spoke over phone on Friday with Taiwanese President Tsai Ing-wen, a move that is likely to infuriate China and complicate US relations with Beijing.
The call was the first such contact with Taiwan by a US president-elect or president since President Jimmy Carter adopted a one-China policy in 1979.
Trump said on Twitter that the Taiwanese leader had initiated the call.
Alex Huang, a spokesman for Tsai, said: "Of course both sides agreed ahead of time before making contact."
The Trump transition team said in a statement that the two leaders noted that "close economic, political and security ties exist between Taiwan and the United States."
Taiwan's presidential office said the two leaders touched on strengthening bilateral interactions and establishing closer cooperation.
There was no immediate comment from China, which is likely to be angered because it views Taiwan as a renegade province.
Washington is Taiwan's most important political ally and sole arms supplier, despite the lack of formal diplomatic ties.
The call comes at a time of worsened Taiwan-China relations since the election of Tsai's pro-independence Democratic Progressive Party (DPP) earlier this year.
The White House responded to the call by saying that the "longstanding policy" on China and Taiwan has not changed.
"We remain firmly committed to our 'One China' policy," said Ned Price, a national security spokesperson for President Barack Obama. "Our fundamental interest is in peaceful and stable cross-Strait relations."
A former diplomat, who helped arrange the call and did not want to be identified, said Chinese officials he spoke to beforehand said they were not troubled by the call because Trump was not yet the president. Trump takes office on 20 January.
Tsai was one of the four world leaders Trump spoke to on Friday, raising questions about whether he is effectively coordinating with the US State Department before reaching out to leaders overseas.
Confused With Trump, China Turns to 93-Year-Old Henry Kissinger
Chinese President Xi Jinping told former US secretary of state Henry Kissinger on Friday that China was watching US politics "very closely", following the presidential election won by Republican Donald Trump.
Trump lambasted China throughout the US election campaign, drumming up headlines with his pledges to slap 45 percent tariffs on imported Chinese goods and to label the country a currency manipulator.
A few days after his victory, Xi told Trump on a telephone call that cooperation was the only choice for China and the United States.
"The presidential election has taken place in the United States and we are now in a key moment. We on the Chinese side are watching the situation very closely. Now it is the transition period," Xi told Kissinger, in remarks made in front of reporters.
"Overall, we would like to see the China-US relationship move ahead in a stable and sustained manner," Xi said.
(With Reuters inputs)
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