China on Sunday made it clear that the 'One China' policy is "non-negotiable" and "no one can change it", in a strong rebuttal to President-elect Donald Trump's plan to use American policy on Taiwan as a bargaining chip.

Chinese Foreign Ministry spokesman Lu Kang said the 'One China' policy is the political foundation of bilateral ties and "is non-negotiable", following Trump's statement that the policy on Taiwan is up for negotiation and that he is not fully committed to it.

"Everything is under negotiation, including One China," Trump told the Wall Street Journal on Friday, questioning the decades-old-policy followed by Washington in its relations with Beijing.

It must be pointed out that there is but 'One China' in the world, and that Taiwan is an inalienable part of China, Lu said in a statement.

The government of the People's Republic of China is the only legitimate government representing China, "which is an internationally recognised fact and no one can change it," Lu said.

"We urge the relevant party in the United States to realise the high sensitivity of the Taiwan issue and abide by commitments made by previous US governments to the One China policy and the principles of the three joint communiques," he said without directly referring to Trump.

Lu urged the US side to properly deal with the Taiwan issue so as to avoid undermining the healthy and steady development of bilateral ties and cooperation in major areas, state-run Xinhua news agency reported.

Since his election, Trump has riled China by holding telephone talks with Taiwanese President Tsai-Ing-wen, who herself is toeing a hardline against Beijing.

China on the other hand is pressuring over 20 countries mainly in Latin America and Africa to not have diplomatic ties with Taipei.

Recently China prevailed over tiny African island Sao Tome and Principe to break off diplomatic ties with Taiwan, which in turn accused Beijing of offering big loans to entice the small countries to move away from Taipei.

Nigeria also broke off all diplomatic relations with Taiwan after the visit of Chinese Foreign Minster Wang Yi few days ago.

Besides a showdown on 'One China' policy after Trump takes over, Beijing also apprehends a trade war as the US Presidential-elect wants to bring about a parity of bilateral trade, which is heavily in favour of China.

China's exports to the US total to about $500 billion against $100 billion of American exports to the Chinese mainland.

Trump accuses China of devaluing its currency to gain more out of its exports.

Trump has also questioned China's island building in the disputed South China Sea and his Secretary of State nominee Rex Tillerson said last week that China should be stopped from accessing the islands.