US President Donald Trump on Wednesday dismissed a report that he accrued losses totalling $1.17 billion in a decade when he was promoting himself as a master dealmaker as a "Fake News hit job".

Trump did not directly acknowledge the losses reported by The New York Times, but in a pair of tweets said real estate developers were entitled to "massive write-offs and depreciation."

"You always wanted to show losses for tax purposes....almost all real estate developers did – and often re-negotiate with banks, it was sport," he said.

"Additionally, the very old information put out is a highly inaccurate Fake News hit job!"

According to the Times, Trump's apparent losses were greater than nearly any other individual American taxpayer, so much so that he managed to avoid paying income taxes for eight of the 10 years.

Trump's federal tax forms from 1985 show he reported $46.1 million in losses from his main businesses, which consisted mainly of casinos, hotels and retail spaces in apartment buildings.

Over the course of the next 10 years, they continued to lose money, with losses totalling $1.17 billion by 1994,the Times said.

The report comes the day after Treasury Secretary Steven Mnuchin denied Democratic lawmakers' request for Trump's more recent tax returns, saying it "lacks a legitimate purpose," raised constitutional questions and threatened taxpayer privacy.

"I am informing you now that the Department may not lawfully fulfil the committee's request," Mnuchin said in a letter to House Ways and Means Committee Chairman Richard Neal.

Mnuchin's refusal after a month of deliberation appeared certain to spark yet another legal clash between the embattled president and congressional Democrats who now control the House of Representatives.