The main findings from special counsel Robert Mueller’s long and contentious investigation into Russian interference in the US presidential elections will not be revealed for at least another day.

While attorney general William Barr spent Saturday reviewing the confidential report on the Trump-Russia investigation, a senior Justice Department official told AP his “principal conclusions” summary for Congress would not be released immediately.

A White House spokesman said they had not received the report or been briefed on its contents.

Hogan Gidley, who met President Donald Trump on Saturday on the golf course near his Mar-a-Lago resort in Palm Beach, Florida, told reporters that the next steps are up to Mr Barr.

The attorney general has said he expected to send his version to the US judiciary committee as soon as this weekend after determining what should be made public.

Mr Mueller sent the attorney general the final report on Friday after a 22-month investigation that cast a dark shadow of Donald Trump’s presidency.

Even with the details still under wraps, the indication that Mr Mueller does not plan to make any additional indictments was welcome news to some in Mr Trump’s orbit who had feared a final round of charges could ensnare more of his associates, including members of the president’s family.

Mr Trump has relentlessly criticised Mr Mueller’s investigation as a “witch hunt, but has stayed uncharacteristically quiet on Twitter while at his Florida golf resort.

Mr Barr said in a Friday letter to the House and Senate judiciary committees that he would share Mueller’s main findings as soon as this weekend.

The Justice Department said the report was delivered by a security officer late on Friday to the office of deputy attorney general Rod Rosenstein, and it was then passed to Mr Barr.

Word of the delivery triggered reactions across Washington, including Democrats’ demands that it be quickly released to the public and Republicans’ contentions that it ended two years of wasted time and money.

House Speaker Nancy Pelosi has told House Democrats that even if there are no further prosecutions from Mr Mueller, his full report must be released to Congress.

Mrs Pelosi sent a letter to colleagues ahead of an “emergency” call with all rank-and-file lawmakers Saturday to discuss where Democrats “go from here” in their oversight of the White House.

She said Mr Barr’s offer to provide Congress with a summary of conclusions was “insufficient.”

Mr Muller arrives at his office on Thursday
Mr Muller arrives at his office on Thursday (Andrew Harnik/AP)

Mr Mueller’s report sought to answer two core questions: Did Mr Trump’s campaign collude with the Kremlin to sway the 2016 presidential election in favour of the celebrity businessman? Also, did Mr Trump take steps later, including by firing his FBI director, to obstruct the probe?

A Justice Department official confirmed that Mr Mueller was not recommending any further indictments, and described the document as “comprehensive”.

That was good news for a handful of the president’s associates and family members dogged by speculation of possible wrongdoing.

They include Donald Trump Jr, who had a role in arranging a Trump Tower meeting at the height of the 2016 campaign with a Kremlin-linked lawyer, and Mr Trump’s son-in-law, Jared Kushner, who was interviewed at least twice by Mueller’s prosecutors.

It was not immediately clear whether Mr Mueller might have referred additional investigations to the Justice Department.

During the investigation, Mr Mueller charged 34 people, including the president’s former campaign chairman, Paul Manafort, his first national security adviser, Michael Flynn, and three Russian companies.

Twenty-five Russians were indicted on charges related to election interference, accused either of hacking Democratic email accounts during the campaign or of orchestrating a social media campaign that spread disinformation on the internet.

Five Trump aides pleaded guilty and agreed to co-operate with Mr Mueller and a sixth, long-time confidant Roger Stone, is awaiting trial on charges that he lied to Congress and engaged in witness tampering.

The conclusion of the investigation does not remove legal peril for the president.

Trump Russia Probe
Copies of a letter from Mr Barr advising Congress that Mr Mueller has concluded his investigation (Pablo Martinez Monsivais/AP)

Mr Trump faces a separate Justice Department investigation in New York into hush money payments during the campaign to two women who say they had sex with him years before the election.

He has also been implicated in a potential campaign finance violation by his former lawyer, Michael Cohen, who says Mr Trump asked him to arrange the transactions.

Federal prosecutors, also in New York, have been investigating foreign contributions made to the president’s inaugural committee.

In his letter to lawmakers, Mr Barr noted the department had not denied any request from the special counsel, something the attorney general would have been required to disclose to ensure there was no political inference.

Mr Trump was never interviewed in person, but submitted answers to questions in writing.