US Attorney General William Barr testifies before the Senate Judiciary Committee on 'The Justice Department's Investigation of Russian Interference with the 2016 Presidential Election' [Nicholas Kamm/AFP]

The United States House Judiciary Committee threatened on Friday to hold Attorney General William Barr in contempt of Congress if he does not comply with a new Monday deadline for Special Counsel Robert Mueller's full, unredacted report and some underlying materials.

The new offer from House Judiciary Committee Chairman Jerrold Nadler comes after the Justice Department missed the committee's earlier deadline for the information. Nadler narrowed his offer in a new letter to Barr on Friday, saying the committee would limit its request for underlying materials to those directly cited in the report.

Nadler said the committee "will move to contempt proceedings and seek further legal recourse" if the department does not comply.

The deadline comes after a week of heightened tension between Democrats and the Trump administration over Barr's handling of Mueller's Russia report.

On Thursday, House Speaker Nancy Pelosi accused Barr of lying to Congress. She was apparently referring to Barr's comments last month during a House Appropriations Committee hearing in which he said he was not aware if Mueller had disagreed with Barr's four-page summary of the investigation.

Earlier this week, it was revealed that Mueller sent a letter to Barr on March 27 - three days after the attorney general sent his four-page summary to Congress - that said Barr's memo "did not fully capture the context, nature, and substance" of the special counsel's investigation.

Barr, speaking before the Senate Judiciary Committee this week, said he had a 15-minute phone call with Mueller after the special counsel sent the letter. He said Mueller "was very clear with me that he was not suggesting that we had misrepresented his report".

Pelosi said that "if anybody else did that, it would be considered a crime".

Skips House panel hearing

Separately on Thursday, Barr failed to show up to a House Judiciary Committee hearing about the Mueller report. The Justice Department said Barr cancelled his appearance over "unnecessary" changes to the format of the hearing, which would have included an extra hour of proceedings to allow for committee lawyers to question the attorney general.

Barr released a redacted version of Mueller's 448-page report last month. It did not establish the Trump campaign conspired with Russian operatives. The investigation did, however, examine "multiple acts by the president that were capable of exerting undue influence over law enforcement investigations".

Mueller did not conclude that President Donald Trump committed obstruction of justice, but did not exonerate him either. Barr and Deputy Attorney General Rod Rosenstein subsequently concluded that Trump did not break the law.

The Trump administration has sought to block staffers and former officials from appearing for hearings or interviews, as well as decline requests for documents from a number of House committees investigating the president.

Trump, who has repeatedly called the Mueller investigation a "witch-hunt", on Friday said it was "time to get back to business".

"The Mueller report strongly stated that there was No Collusion with Russia," he tweeted. "No more costly & time consuming investigations."

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