US President Donald Trump has defended sweeping tariffs on imports that sent shockwaves through global stock markets, saying "sometimes you have to take medicine to fix something".

Speaking to reporters aboard Air Force One late on Sunday, he said jobs and investment would return to the US to make it "wealthy like never before".

Trump's top officials stressed that the tariffs - announced last week - would be implemented as planned, playing down recession fears.

Just hours after Trump's comments, stock markets plunged in Asia early on Monday, with Japan's Nikkei 225 dropping by 6.3%, and Hong Kong's Hang Seng losing 9.8%.

On Friday, all three major stock indexes in the US fell more than 5%, while the S&P 500 dropped almost 6% in the worst week for the US stock market since 2020.

Saudi Arabia's stock exchange - which trades on Sundays - ended nearly 7% lower, its biggest daily loss since the pandemic, state-owned media said.

US banking giant JP Morgan has predicted a 60% chance of a US and global recession following Trump's tariffs announcement.