WASHINGTON (AFP)

US President Donald Trump's threat of fresh tariffs on imports from China will stack on an already steep rate due to take effect midweek, the White House told AFP on Monday.

Trump said in a Truth Social post that he would impose further tariffs of 50 percent on China from April 9. Shortly afterwards, the White House confirmed that these would add to a 34 percent rate that Trump earlier planned for Wednesday -- taking the overall additional duties this year to 104 percent.