WASHINGTON - Almost 500 former US Justice Department officials said on Monday in a joint statement that the Mueller report's findings would justify obstruction charges against US President Donald Trump if he were not currently occupying the White House.

US Attorney General William Barr has said he found insufficient evidence in Mueller's report to conclude that Trump obstructed justice. Special Counsel Robert Mueller himself made no formal finding one way or the other on that question.

"To look at these facts and say that a prosecutor could not probably sustain a conviction for obstruction of justice ... runs counter to logic and our experience," said the statement, signed by Justice Department lawyers who served Republican and Democratic presidents stretching back to the 1950s.

As of late Monday, 467 officials had signed the letter.

Mueller's report unearthed numerous links between Trump's 2016 presidential campaign and various Russians, but it concluded there was insufficient evidence to establish that the campaign engaged in a criminal conspiracy with Moscow.

It also described attempts by Trump to impede Mueller's probe, but stopped short of declaring Trump committed a crime.

Under a long-standing Justice Department Office of Legal Counsel policy, a sitting president cannot be charged with criminal activity.

"Each of us believes that the conduct of President Trump described in Special Counsel Robert Mueller's report would, in the case of any other person not covered by the Office of Legal Counsel policy ... result in multiple felony charges for obstruction of justice," the statement said.

A Justice Department spokeswoman referred to prior statements by Barr, in which he said Mueller had not provided enough evidence to bring a successful obstruction case.

A Mueller spokesman declined to comment.

Among signers of the statement were Donald Ayer, who was the Justice Department's No 2 official under Republican president George H.W. Bush, and Bill Weld, a former head of the Justice Department's criminal division under Republican president Ronald Reagan. Weld is making a bid to challenge Trump for the 2020 Republican presidential nomination.

Weld's presidential campaign confirmed he signed the statement and Ayer said he also signed it.

The statement was coordinated by a nonprofit, nonpartisan group called Protect Democracy, which says it was formed "to prevent our democracy from declining into a more authoritarian form of government".

The White House did not immediately respond to a request for comment.

The statement came as Democrats in the House of Representatives threaten to hold Barr in contempt for not giving them a full, unredacted version of the Mueller report.

Reuters