Donald Trump further said China was devaluing their currency and they're also pouring money in.

US President Donald Trump on Friday warned of imposing substantial tariffs on imports from China if the trade negotiations does not go well.

"China has to do a lot of things to turn it around. But you'll be seeing. They've got to do a lot of things. It (tariff increase) goes on September 1," Donald Trump said a day after he announced to impose 10 per cent tariff on Chinese products worth nearly USD 300 billion.

This is in addition to the 25 per cent import tariff on Chinese products worth USD 250 billion.

The next round of the US-China trade talks is scheduled for September.

"Frankly, if they don't do, I can always increase it very substantially. In other words, I could increase it - if I wanted to, I could increase it to a very much higher number," he said.

Observing that the US was "so far behind" China before he became the President, Donald Trump said America had been treated badly.

"And I don't blame China. I blame our past leaders, our past presidents, our past trade representatives. They've done a terrible job," he said.

"We can't just go and make an even deal with China. We have to make a much better deal. Because, right now, they have a very unfair playing field, and I'm turning it around. We are getting 25 per cent of USD 250 billion and now we'll be getting 10 per cent of probably close to USD 350 billion. It's a lot of money," he said.

Donald Trump further said China was devaluing their currency and they're also pouring money in.

"Their currency is going to hell, but they're also pouring money in. That will totally pay for the tariffs. The tariffs are not being paid for by our people; it's being paid for by China because of devaluation and because they're pumping money in," he said.

Donald Trump said the US was taking in billions of dollars from China.

"We never took in 10 cents from China. Out of that many billions of dollars, we're taking a part of it and we're giving it to the farmers because they've been targeted by China. They come out totally whole. So, you interviewed the wrong farmer, but that's all right," said the US President.

