US President-elect Donald Trump spoke by phone on Friday with President Tsai Ing-wen of Taiwan, a move that is likely to infuriate China, which considers the self-ruled island its own, and complicate US relations with Beijing.

The conversation was the first such contact with Taiwan by a US president-elect or president since President Jimmy Carter switched diplomatic recognition from Taiwan to China in 1979, recognising Taiwan as part of “one China”.

Trump said on Twitter that Tsai had initiated the call. “The President of Taiwan called me today to wish me congratulations on winning the Presidency. Thank you!” he said.

Alex Huang, a spokesman for Tsai, said: “Of course both sides agreed ahead of time before making contact.”

The two noted that “close economic, political and security ties exist between Taiwan and the United States,” the Trump transition team said in a statement.

Taiwan's presidential office said the two discussed 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, to be united by force if necessary.

Washington is Taiwan's most important political ally and sole arms supplier, despite the lack of formal diplomatic ties.

“Interesting how the US sells Taiwan billions of dollars of military equipment but I should not accept a congratulatory call,” Trump said in another tweet.

Trump has eschewed tradition in other calls with foreign leaders since he won the US election, prompting the White House to encourage him to make use of the diplomatic expertise and counsel of the State Department.

China referred to the call between Trump and Tsai Ing-Wen as a "petty action" by Taiwan.

“This is just the Taiwan side engaging in a petty action, and cannot change the 'one China' structure already formed by the international community,” Chinese Foreign Minister Wang Yi said at an academic forum, a Hong Kong-based Phoenix Television reported.

“I believe that it won't change the longstanding one China policy of the United States government. The 'one China' principle is the cornerstone of the healthy development of Sino-U.S. ties, and we hope this political basis is not interfered with or damaged in any way.”

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 “longstanding policy” on China and Taiwan had not changed.

“We remain firmly committed to our 'one China' policy,” said Ned Price, a national security spokesman for President Barack Obama. “Our fundamental interest is in peaceful and stable cross-Strait relations.”

Trump adviser Kellyanne Conway said on CNN that Trump was “well aware of what US policy has been” on Taiwan.

Administration officials said Trump's team did not alert the White House about the call ahead of time. Randy Schriver, a former deputy assistant secretary of state responsible for East Asia, including Taiwan, under former President George W. Bush said he believed the call was “primarily a courtesy.”

“China should have no objection... They know better than anyone that contact between leaders does not violate a U.S. One China Policy,” he said.

'Seat of his pants'

However, Gerrit van der Wees, a former Dutch diplomat who lobbies on behalf of Taiwan, said the call indicated Trump would be less bound by conventions and restrictions in foreign policy and was “signalling a broader change in US policy towards Taiwan.”

Advisers to the Republican president-elect have indicated that he is likely to take a more robust policy toward China than Obama, a Democrat, and that Trump plans to boost the US military in part in response to China's increasing power in Asia.

However, details of his plans remain scant.

Senator Chris Murphy, a member of the Senate Foreign Relations Committee, said Trump was entitled to change policy, but his approach was potentially dangerous.

“Foreign policy consistency is a means, not an end. It's not sacred. Thus, it's Trump's right to shift policy, alliances, strategy,” Murphy, a Democrat, said in a note on Twitter.

But he added: “What has happened in the last 48 hours is not a shift. These are major pivots in foreign policy w/out any plan. That's how wars start.”

China has claimed sovereignty over Taiwan since 1949, when Mao Zedong's Communist forces won the Chinese civil war and Chiang Kai-shek's Nationalists fled to the island. Beijing has vowed to bring Taiwan under its rule.

Earlier this week Trump spoke to Pakistani Prime Minister Nawaz Sharif and praised him, according to the Pakistani leader's office, as a “terrific guy.”

Islamabad and Washington have seen relations sour in recent years over US accusations that Pakistan shelters Islamist militants who kill US soldiers in Afghanistan, a charge denied by the South Asian nation.

Also on Friday, Trump invited Philippine leader Rodrigo Duterte to the White House next year during what a Duterte aide said was a “very engaging, animated” phone conversation. Duterte has openly insulted Obama, who cancelled a planned meeting with him in September.

A statement issued by Trump's transition team made no mention of the invitation. The transition team said that Trump also spoke on Friday to Afghan President Ashraf Ghani and Singapore Prime Minister Lee Hsien Loong.

Winston Lord, who was US ambassador to China from 1985-89 and is a former assistant secretary of state for East Asian and Pacific affairs, said the strategic importance of Trump's Taiwan call was unclear.

“Like so many things with Trump, who knows? This man is ignorant about foreign policy and is flying by the seat of his pants, so it is difficult to assess the significance.

“Having said that, I have no problem with his talking to Madame Tsai; Taiwan is a good friend and although our relations are unofficial, I think it's important to maintain close bonds with Taiwan.”

Trump and Chinese President Xi Jinping spoke by telephone on Nov. 14. Xi stressed that cooperation was the only choice for relations between the world's two largest economies, and Trump said that the two had established a “clear sense of mutual respect.”

Trump lambasted China throughout the US election campaign, drumming up headlines with pledges to slap 45 per cent tariffs on imported Chinese goods and label the country a currency manipulator on his first day in office.

Douglas Paal, a former official of the U.S. National Security Council who served as US representative to Taiwan from 2002-2006, said nothing Trump had said in the campaign suggested he wanted to rebuild the relationship with Taiwan at the expense of the China relationship.

“From the information I have so far, this is a standalone item,” Paal said, “but the Chinese will feel the need to make a major protest so there isn't more of this.”