Donald Trump has heralded his record on workers, vowing to be a voice for the working classes on the campaign trail, but the head of a global unions group is not convinced.

International Trade Union Confederation chief Luc Triangle told AFP that Trump's previous years proved he could not be trusted in office.

"I don't believe him, knowing what he did in the first four years. He was not the president of workers," Triangle said in an interview at the World Economic Forum in Davos, Switzerland.

By coincidence of timing, the forum began just as Trump was sworn in on Monday as the United States' 47th president.

Trump, who spurred trade wars during his first term in office between 2017 and 2021, has vowed to impose sweeping new tariffs against commercial partners like China as well as Washington's strongest allies including Canada and the European Union.

In his inaugural address, Trump promised tariffs and taxes on other countries "to enrich our citizens", and later the same day said he could impose 25 percent tariffs on Canada and Mexico as early as February 1.

The tariffs, which Trump may extend to other countries, would fuel trade tensions that could have serious consequences for workers, Triangle said.

"A trade war is for no one a good solution. It creates uncertainty. It can also affect companies, sectors, jobs," Triangle said.

Several economists have warned that Trump's campaign promises - such as hefty duties and deporting illegal immigrants - risk pushing up the prices of goods in the United States and beyond.

According to the US think tank Peterson Institute, the policies could see inflation climb by more than four percent in the worst case.

"Inflation is always an attack on the purchasing power of workers because they are never, in almost no country, fully compensated... by a wage increase compensating the inflation," Triangle said.

He said that "we will see now what Trump will deliver", and that workers would look to what "concrete actions" he takes.

While Trump is "very easy to understand" and his language is "simplistic", it is also like slogans, Triangle added.

"The previous president, Joe Biden, did a remarkable job. He was the most worker-centred president in the history of the United States."

AFP