Trump has authority to order US companies to stop doing business with China: Mnuchin

US President Donald Trump has the authority to order American companies to stop doing business with China, his Treasury Secretary Steven Mnuchin said on Sunday, amidst escalating trade war with the world's second largest economy.

Trump on Friday ramped up his tariff war with China, hiking the existing and planned tariffs on a total of USD 550 billion in Chinese goods, in response to new tit-for-tat levy hikes announced earlier that day by Beijing on USD 75 billion of American imports.

The US President can make such an order only if he declares national emergency, but he has not done so, Mnuchin said, adding that Trump is asking American companies to look for alternatives.

"He (Trump) would have the authority to do that under - if he declared an emergency. He has not done that. I think what he was saying is he's ordering companies to start looking because he wants to make sure - to the extent we are in an extended trade war - that companies don't have these issues and move out of China," Mnuchin told Fox news in an interview.

The Trump administration wants them to be in places where the trading partners respect the US and trade with them fairly, he said.

Early this week, Trump said the US Congress in 1977 had passed a National Emergency Act, under which he can make such an order to American companies.

Responding to a question, Mnuchin said that the president had lots of options, but his first choice is to have fair and reciprocal trade.

"The reason why we put on tariffs is for the last two and a half years, we've been working with China to rebalance the trading relationship and it hasn't rebalanced. The trade deficit has grown significantly despite assurances from China that we would improve this," he said.

Mnuchin said when the US and China were close to a trade deal, the President was happy, but the Chinese backed off.

"So, the president does have lots of authorities. We use these authorities successfully with Mexico on certain issues there. We now are close to hopefully having the United States-Mexico-Canada Agreement (USMCA) passed.

"We had a terrific meeting with Canada today on this, and we're looking forward to getting that agreement passed," he said.

Mnuchin said Trump shares a good friendship with Chinese President Xi Jinping and the latest round of tariff announcement by the US "was not intended to send a message" that Xi is his enemy in the sense of all these different areas.

"We are very hopeful that there will be a humane solution in Hong Kong. We are obviously watching what's going on there. The president again reiterated he thinks that President Xi sat down with the protesters. He could get this over with in a few hours. So, we're hopeful that there will be calm in Hong Kong," the Treasury Secretary said.