Mnuchin's remarks came in response to accusations from Chuck Schumer, the top Democrat in the Senate, that he had urged Trump to soften his stance in the trade talks with Beijing.

"I was pleased to review your letter... that strongly supports President Trump's efforts to hold the Chinese government accountable for its longtime 'predatory trade policies,'" Mnuchin said.

"We welcome all allies in this ongoing effort to counter China's unfair economic practices and to advance the president's pro-growth, pro-America agenda."

In a letter on Friday, Schumer -- as well as Oregon's Ron Wyden, the top Democrat on the Senate Finance Committee, and Sherrod Brown, who represents the key industrial swing state of Ohio -- said they were "very troubled" by reports that Mnuchin had called for the American side to "back down."

Trump and Chinese officials projected optimism last week after two days of negotiations aimed at reaching a trade agreement before a March 1 deadline, after which US tariffs on Chinese goods are due to rise sharply.

Beijing has offered to buy more American exports, including agricultural goods, to help re-balance China's soaring trade surplus with the United States.

But US officials, as well as Japan and the European Union, also accuse China of unfair trade practices, including the forced transfer and alleged theft of intellectual property as well as massive state intervention in markets.

In Friday's letter, the Democrat senators said they worried Washington would accept "merely a trade balance recalibration" rather than pursue fundamental changes to Chinese economic policy.

The trade war as also sparked divergences within Trump's Cabinet, with Mnuchin widely seen as less eager for confrontation than US Trade Representative Robert Lighthizer, who is leading the talks, and White House trade advisor Peter Navarro.

The two sides have slapped tariffs on $360 billion in two-way trade, which has weighed on the manufacturing sectors in both countries.