“This kind of swinging and contradiction simply tells us that [Trump] does not truly care about whether Hong Kong is in chaos or in good shape. He just uses Hong Kong as a bargaining chip to put pressure on China in the trade negotiations.”

It added that economic and trade issues should not be politicised and attempts to use Hong Kong as a bargaining chip would be in vain.

“If it weren’t for the trade talks, Hong Kong would be in much bigger trouble. I think it would’ve be much more violent,” Trump told reporters at the White House on Friday.

“I really believe China wants to make a deal, and they know it puts us in a very bad position if there’s not a humane way of handling the problems.

“And I’ve let them know, look, handle it in a humane fashion,” he said. “And we’ll see. But I do believe that because of what I’m doing with trade, that’s very much keeping down the temperature in Hong Kong.”

Trump also said tariff increases on Chinese goods from Sunday would not be delayed despite the more conciliatory language used by the two sides in recent days. Duties on US$300 billion of imports from China will be raised from 10 per cent to 15 per cent.

It is not the first time the American president has linked the Hong Kong protests to the US-China trade war. Earlier this month, Trump warned that trade talks with China would be hampered if Beijing used violent means to crack down on the protests.

The mass anti-government demonstrations in the city since early June were triggered by a now-shelved extradition bill that would have allowed criminal suspects to be transferred to mainland China and have expanded to a wider call for democratic reform.

David Ko Chin, managing director of Basis Point Consulting, which specialises in investment and financial markets in Australia and Asia, said the Hong Kong protests were an area for Washington to apply pressure on Beijing as it sought to gain the upper hand in the trade negotiations.

He added that Trump had used similar tactics during other trade talks, including with Japan and Europe, in the past two years.

“[Trump] is not doing this for the love of the Hong Kong people,” Chin said. “So whatever decision he makes on the Hong Kong situation, it is [ultimately] about making America great again.

“As part of the wider cold war mentality of containing China, this situation is an opportunity [for the US] that has arisen during the negotiations.”

The latest round of tit-for-tat tariffs between the world’s two largest economies is a further sign that there is no end in sight for the trade war, amid the growing threat of a global economic slowdown. Beijing last week announced new retaliatory tariffs on US goods – including a 5 per cent duty on crude oil that will also take effect from Sunday – and Washington responded with another plan to further increase duties on Chinese products.

Uncertainty about when or how the dispute could end has roiled markets and complicated long-term investment plans. Andrew Hunter, a senior US economist at Capital Economics, said it was increasingly hard to see anything other than a continued escalation in the dispute, even though Trump’s tone seemed to have softened.

“The direct impact of [the new] tariffs should be manageable, but there is a risk that uncertainty over the outcome of the conflict starts to weigh more heavily on the economy. So far, however, there is only limited evidence of that in the data,” Hunter said.

But China noted that the negotiations were unpredictable, and there could still be further escalations in either the trade war or the situation in Hong Kong.

Beijing has moved more paramilitary troops and equipment into Shenzhen, which borders Hong Kong, where they have carried out anti-riot drills – a move seen as sending a warning to the city.

The city’s leader, Chief Executive Carrie Lam Cheng Yuet-ngor, this week left the door open to invoke the Emergency Regulations Ordinance – granting a wide range of emergency powers – for the first time in more than 50 years to quell the protests, which legal experts said could deal a blow to the city’s rule of law.

Meanwhile, the Group of Seven leaders issued a joint statement backing Hong Kong’s autonomy, as laid out in the 1984 Sino-British Joint Declaration, after a meeting in France.

US lawmakers also reintroduced a proposed Hong Kong Human Rights and Democracy Act, which if passed would require the US government to conduct an annual assessment of Hong Kong’s autonomy and would give the US president power to take action against people “complicit in suppressing basic freedoms in Hong Kong”.

Terence Chong Tai-leung, an economist at Chinese University of Hong Kong, said Trump was “just trying to claim credit” with his latest comments.

“[However] if Trump had the ability to convince the protesters to refrain from using violence, then that would temper Hong Kong’s situation. But in that case, it would mean he is intervening with the protests,” Chong said, referring to Beijing’s repeated accusation that foreign powers were fuelling the unrest in the city.

“Hong Kong is being used as a chess piece by the US to achieve its aim of raising tariffs,” he said. “China will likely ignore Trump on Hong Kong … There is no benefit to China in continuing negotiating with the US when tariffs are going up.”