Concerns about a heightened trade war between the world's two largest economies are mounting and observers have been closely watching for signs of relief that could emerge from a call between Trump and Xi.

Trump was asked in a Fox News interview aired Monday if he had spoken with Xi since starting his second term and replied: "Yeah... I have talked to him and I talk to his people too."

However, in response to a question during a regular news briefing on Tuesday seeking to confirm the call, China's foreign ministry answered simply by referring to a conversation that took place three days before Trump's inauguration.

"On January 17, President Xi Jinping had a phone conversation with US President Donald Trump. The Chinese side has released a relevant press release," ministry spokesman Guo Jiakun said.

Trump has announced hefty tariffs on major trading partners including China, Mexico and Canada since taking office, lambasting unfair trade practices as well as the countries' alleged roles in a devastating fentanyl crisis in the United States.

However, he agreed last week to a 30-day pause on new tariffs for Mexico and Canada following conversations with the leaders of the two countries.

But a 10 percent US tariff on Chinese products came into effect as scheduled, prompting Beijing to take retaliatory measures.