WASHINGTON: A US federal judge on Tuesday rejected former president Donald Trump's legal campaign to prevent Congress from gaining access to his tax returns, officials said.

Judge Trevor McFadden, a Trump appointee to the district court in Washington, said the former US leader's legal team, which has been fighting Democratic efforts to see his tax filings for two years, were "wrong on the law."

The ruling is a major blow to Trump, who has fought tooth and nail to keep his tax returns private, despite campaign promises in 2016 to release them.

Trump said the effort by the Democratic-led House of Representatives was politically motivated.

Democratic Congressman Richard Neal, chairman of the House Ways and Means Committee that led the effort to secure access to the tax returns, said the ruling was "no surprise, the law is clearly on the Committee's side."

"I am pleased that we're now one step closer to being able to conduct more thorough oversight of the IRS's mandatory presidential audit program," he said in a statement.

The Justice Department in August ordered the Treasury to provide the congressional committee with six years of records that Trump had refused to make public.

US presidents are not required by law to release details of their personal finances, but every US leader since Richard Nixon has done so.

The congressional committee has the right to make the returns public, but the judge's ruling included a cautionary note against that move.

"It might not be right or wise to publish the returns, but it is the Chairman's right to do so," McFadden wrote.

"Congress has granted him this extraordinary power, and courts are loath to second guess congressional motives or duly enacted statutes. The Court will not do so here and thus must dismiss this case," he said.