China vows to retaliate 'immediately' to U.S. trade tariffs

China vowed to "immediately" retaliate to US tariffs on Friday as Washington moved closer to imposing duties that could trigger a trade war.

US President Donald Trump is due to unveil later Friday a final list of roughly $50 billion in Chinese imports that would face punishing tariffs, though his administration has not yet publicly said when the measures will be imposed.

"If the US side adopts unilateral protectionist measures and damages China's interests, we will immediately react and take necessary measures to firmly safeguard our legitimate rights and interests," said foreign ministry spokesman Geng Shuang during a regular news briefing.

The news sent Shanghai stocks spiralling downwards Friday to end at the lowest level since September 2016.

China has pledged that any tariffs will void progress made in recent trade talks between Beijing and Washington and has drawn up its own list of $50 billion in US goods to target.

"All the results from the negotiations will not go into effect," Geng repeated, and added China's commerce ministry had made a formal response to the US's unilateralism in early April when the Trump administration first unveiled the tariffs.

The response included tariffs on US goods roughly equal in value to those to be sanctioned by the US.

China's list included America's largest exports to China such as soybeans and a slew of other US products including cars, frozen beef, and whiskey.

If implemented, the tariffs will dent economic growth on both sides of the Pacific, analysts say.