Image copyright AFP/Getty Image caption If the US moves ahead with tariffs, China has threatened to retaliate with tariffs on US items such as soybeans

The US has said it plans to impose 25% tariffs on $50bn worth of Chinese imports "shortly" after mid-June.

Critics had accused the administration of going soft on China after Treasury Secretary Steven Mnuchin said tariffs were on hold while the two sides continue trade talks.

But the White House said on Tuesday that a final list of imports slated for tariffs will be published by 15 June.

China said it was both "surprised and unsurprised" by the move.

In a statement, China's Commerce Ministry called on the US to act in the spirit of earlier joint comments.

It said: "This is obviously contrary to the consensus reached between the two sides in Washington not long ago."

The tougher line from the White House comes ahead of another round of negotiations.

US Commerce Secretary Wilbur Ross is scheduled to travel to China this week.

The trip follows talks in Washington in May. Those ended with a pledge by the Chinese to buy more US agricultural and energy products, but few firm commitments.

Where did this start?

The tariffs and investment restrictions, as well as a case brought by the US against China before the World Trade Organisation, are the outcome of an investigation the US launched last year into intellectual property practices in China.

The US is pushing China to reduce taxes on imports and stop practices that allegedly encourage transfer of intellectual property to Chinese companies, such as requirements that foreign firms share ownership with local partners to access the Chinese market.

However, the administration is torn between groups worried about a trade war and hardliners calling for stronger action.

US officials published a first draft of items targeted for potential tariffs this spring, triggering a period for comments and feedback.

The initial list included about 1,300 items, including medical devices and industrial machinery.

The White House said on Tuesday: "The final list of covered imports will be announced by June 15, 2018, and tariffs will be imposed on those imports shortly thereafter."

The White House also said it plans to announce new measures to restrict Chinese investment "related to the acquisition of industrially significant technology" by 30 June. Those would also be implemented "shortly thereafter".

On Tuesday, Chuck Schumer, who leads Democrats in the Senate, praised the plans.

He said: "While obviously more details are needed, this outline represents the kind of actions we have needed to take for a long time, but the president must stick with it and not bargain it away."

If the two sides fail to reach an agreement and the US moves forward with tariffs, Chinese officials have said they plan to retaliate with tariffs of their own on US exports such as soybeans.

The White House said on Tuesday: "Discussions with China will continue on these topics, and the United States looks forward to resolving long-standing structural issues and expanding our exports by eliminating China's severe import restrictions."