Washington: US President-elect Donald Trump has spoken with Taiwan's president, a major departure from decades of US policy in Asia and a breach of diplomatic protocol with ramifications for the incoming president's relations with China.

Trump spoke by phone with Taiwanese President Tsai Ing-wen on Friday, Trump spokeswoman Hope Hicks said. The conversation was first reported by the Financial Times and the Taipei Times.

The call is the first known contact between a US president or president-elect and a Taiwanese leader since the United States broke diplomatic relations with the island in 1979. China considers Taiwan a province, and news of the official outreach by Trump is likely to infuriate the regional military and economic power.

Trump repeatedly criticised China during his campaign, promising to brand the country a currency manipulator, which could also add tension to relations with the Pacific power. He blamed China for undermining US manufacturing jobs by selling artificially cheap exports.