Trump vows response to China tariffs


But as markets in the US, Asia and Europe tumbled, the White House offered no further details or explanation of Trump's intentions.

Instead, the president tweeted he would be responding to China's tariffs on Friday afternoon.

"This is a GREAT opportunity for the United States," he wrote.

The US has said it plans to impose 10 per cent tariffs on $US300 billion ($A444 billion) of Chinese goods in two steps, on September 1 and December 15.

China responded on Friday with new tariffs on $US75 billion ($A111 billion) of US products in retaliation, deepening a conflict over trade and technology that threatens to tip a weakening global economy into recession.

China also will increase import duties on US-made autos and auto parts, the Finance Ministry announced.

Tariffs of 10 per cent and 5 per cent will take effect on two batches of goods on September 1 and December 15, the ministry said in a statement.

It gave no details of what goods would be affected but the timing matches Trump's planned duty hikes.

The announcement comes as leaders of the Group of 7 major economies prepare to meet in France this weekend.

Washington is pressing Beijing to narrow its trade surplus and roll back plans for government-led creation of global competitors in robotics, electric cars and other technology industries.

"Our great American companies are hereby ordered to immediately start looking for an alternative to China, including bringing ... your companies HOME and making your products in the USA. I will be responding to China's Tariffs this afternoon," Trump tweeted on Friday.

The White House did not immediately respond to questions about what authority the president has to order private companies to change their business practices.