Beijing: China said on Thursday that it does not want a trade war to start if the US imposes the first round of tariffs on imported Chinese products, but if it does then Beijing will be forced to react in the interests of the country and its people.

On Friday, the US will initially impose a set of tariffs on 818 Chinese items worth about $34 billion. Separate measures affecting 284 products worth about $16 billion could take effect following a review and public comment process.

China has repeated several times that it was not going to impose tariffs before the US does so, Commerce Ministry spokesperson Gao Feng said at a press conference here.

"US measures are essentially attacking global supply and value chains. To put it simply, the US is opening fire on the entire world, including itself," he was quoted as saying by Efe news.

"China will not bow to threats or blackmailing and our resolve to safeguard global free trade and the multilateral mechanism will not waver."

Nearly 50 per cent of the products subjected to tariffs, accounting for more than $20 billion, are manufactured by foreign firms in China, a majority of them American, Gao said.

He also said that the US move amounts to violation of provisions of the World Trade Organisation's General Agreement on Tariffs and Trade 1994 and of the Agreement on Safeguards.

Gao called on all countries to unite against protectionism and unilateralism. "China will work with other countries to fight against the regressive tide of backward, outdated and inefficient protectionism and unilateralism and will maintain a stable and predictable global economic and trade environment."

Beijing had already warned President Donald Trump that if tariffs on Chinese products are imposed, it will react with tariffs on 545 goods imported from the US.

Despite warning of retaliatory tariffs, the spokesperson expressed China's intention to protect the interests of all the firms based in China and help them diffuse the potential impact of a trade war.