US President Donald Trump has announced a base-line rate of 10 per cent on all imports and higher individualised rates for dozens of countries that included 26 per cent for India, 34 per cent for China and 20 per cent for the EU.

Other countries hit with higher rates are the UK, Japan, South Korea, Indonesia, Taiwan, the EU, Vietnam, Cambodia, Switzerland, Bangladesh, Pakistan and Sri Lanka.

"India, very, very tough," President Trump said on Wednesday, reading out the new levies from a chart.

"Very, very tough. The Prime Minister just left. He's a great friend of mine, but I said, 'You're a friend of mine, but you're not treating us right.' They charge us 52 per cent. You have to understand, we charge them almost nothing," Trump said.

The Indian levy on imports from the US -- as calculated by the US in this instance follows a formula that includes both monetary and non-monetary levies and barriers. The new American levy on imports from India was put at half, 26 per cent.

"Because we are being very kind, we're kind people, very kind," Trump said, explaining the new levies. "We will charge them approximately half of what they are and have been charging us, so the tariffs will not be reciprocal. I could have done that, I guess, but it would have been tough for a lot of countries who didn't want to do that."

President Trump was referring to a visit by Prime Minister Narendra Modi to the White House in February as among his first foreign visitors. Trump spoke warmly of his friendship with the Prime Minister, as he has on many occasions.

Reading out from the chart, Trump said the Chinese levy on US imports added up to 67 per cent, "so we're going to be charging a discounted reciprocal tariff of 34 per cent, I think; in other words, they charge us, we charge them, we charge them less."

For the EU, he said, "They're very tough, very, very tough traders. You know, you think of the European Union, very friendly. They rip us off. It's so sad to see. It's so pathetic... We are going to charge them 20 per cent... essentially half."

Vietnam, he said, had "great negotiators, great people. They like me. I like them. "The problem is they charge us 90 per cent. We're going to charge them 46 per cent tariff."

Taiwan, which he said, "took all of our computer chips and semiconductors. Taiwan, where they make, they took all of our computer chips and semiconductors. We used to be the king, right? We were everything. We had all of it. Now we have almost none of it, except the biggest company is coming in. They're going to have, we're going to end up with almost 40 per cent."