South Korean carmaking giant Hyundai has unveiled $21bn (£16.3bn) of investment in the US just days before President Donald Trump is set to impose new tariffs on trading partners.

The plan includes a new $5.8bn steel plant in the southern state of Louisiana.

Hyundai also said it will expand its American vehicle production and invest billions of dollars in new technology including autonomous driving and artificial intelligence (AI).

"This investment is a clear demonstration that tariffs very strongly work," Trump said during the event at the White House on Monday.

He added that more tariffs on vehicle imports are likely to be announced this week.

Hyundai said the new steelmaking facility will produce more than 2.7 million metric tons of steel a year and create more than 1,400 jobs.

It is expected to make steel for Hyundai's plants in Alabama and Georgia.

The announcement also included plans to invest $9bn to boost the firm's production in the US to 1.2 million vehicles a year by 2028.

Hyundai also said it had earmarked $6bn to expand partnerships with US firms to develop technologies including self-driving vehicles, robotics and AI.

On Wednesday, Hyundai Motor is set to hold an opening ceremony for a new $7.59bn car and battery factory in Georgia.

It already has a manufacturing facility in Alabama and its affiliate Kia has a factory in Georgia.

When fully operational, the three plants will have capacity to make a million vehicles a year, the company said.

Hyundai also said it would buy $3bn worth of liquefied natural gas (LNG) from the US.

Since Trump's return to power several companies have announced plans to make major investments in the US.

But some of the announcements have been reiterations of previously publicised plans.

During the Biden administration, Hyundai said it would invest about $10bn in new technology by 2025.

The latest announcement came a little over a week before 2 April, when Trump has said he will impose reciprocal tariffs on countries around the world.

The new round of import taxes could potentially target Hyundai's home country South Korea, which has a large trade surplus with the US.

Last month, Trump ordered a 25% import tax on all steel and aluminium entering the US.

He also extended the levies to include hundreds of metal products from nuts and bolts to drink cans.

In recent weeks, US carmakers, including General Motors and Ford, have been calling on the US president to exempt imports of cars and vehicle parts from new tariffs.