US President Donald Trump announced an additional 100 percent tariff on China on Friday, reigniting his trade war with Beijing in a row over export curbs on rare earth minerals.

Trump said the extra levies, plus US export controls on "any and all critical software," would come into effect from November 1 in retaliation for what he called Beijing's "extraordinarily aggressive" moves.

"It is impossible to believe that China would have taken such an action, but they have, and the rest is History," he said on Truth Social.

Stock markets fell as the simmering trade war between the United States and China reignited, with the Nasdaq down 3.6 percent and the S&P 500 down 2.7 percent.

Chinese goods currently face US tariffs of 30 percent under tariffs that Trump brought in while accusing Beijing of aiding in the fentanyl trade, and over alleged unfair practices.

China's retaliatory tariffs are currently at 10 percent.

Trump had threatened the tariffs hours earlier in a lengthy surprise post on his Truth Social network that said China had sent letters to countries around the world detailing export controls on rare earth minerals.

Rare earth elements are critical to manufacturing everything from smartphones and electric vehicles to military hardware and renewable energy technology. China dominates global production and processing of these materials. (AFP)