A redacted version of Special Counsel Robert Mueller’s report on Russian interference in the 2016 US election and contacts between Moscow and President Donald Trump’s campaign will be released on Thursday.

Justice Department spokeswoman Kerri Kupec did not provide a precise time, but said the report, which Attorney General William Barr has described as nearly 400 pages long, will be released both to the US Congress and the public in the morning.

Moments after the announcement, the Republican president went on Twitter to make another attack on Mueller’s team and derided the “Russia Hoax”.

The Mueller investigation has cast a cloud over the presidency of Trump, who has often called it a politically motivated “witch hunt”.

Mueller turned over a copy of his confidential report to Barr on March 22, ending his 22-month-long inquiry. Two days later, Barr released a four-page letter summarising what he said were Mueller’s primary conclusions.

In that letter to congress, Barr said Mueller’s investigation did not establish that members of Trump’s election campaign conspired with Russia.

Barr also wrote that Mueller presented evidence “on both sides” about whether Trump obstructed justice, but he did not draw a conclusion one way or the other.

The letter that William Barr, the attorney general, sent to Congress informing them of the receipt of Robert Mueller’s report. Photo: NYT

Barr said he reviewed Mueller’s evidence and made his own determination that Trump did not commit the crime of obstruction of justice.

The attorney general has been under pressure from Democrats to release the full report without redactions. Barr, a Trump appointee, has pledged to be as transparent as possible. But he has said he will redact some sensitive information, including grand jury information and information about US intelligence-gathering.

After Barr released his four-page letter, Trump claimed “complete and total exoneration,” condemned “an illegal takedown that failed” and accused unnamed political enemies of treasonous acts.

The redactions in the report will be colour-coded by category, according to Barr, explaining the reasons that parts are blacked out.

Since Barr released his letter, Trump has set his sights on the FBI, and accused the Justice Department of improperly targeting his campaign.

Last week, Barr told a US Senate panel he believed that “spying” did occur on Trump’s campaign, and he plans to investigate whether it was properly authorised.

“I think spying did occur,” Barr, the top US law enforcement officer, told the lawmakers.

“But the question is whether it was adequately predicated.”

Barr’s comments were criticised by Democrats, who are already sceptical of how the attorney general has handled the report’s release.

-AAP