U.S. Attorney General William Barr testifies before a Senate Appropriations Subcommittee hearing on the proposed budget estimates for the Department of Justice in Washington, U.S. April 10, 2019.

U.S. House Judiciary Committee Chairman Jerrold Nadler said on Monday that Attorney General William Barr must testify before his panel on Thursday, despite Barr's reported objections to the format for questions that Democrats intend to use.

"We've been very clear. Barr has to come. He has to testify. It's none of the business of a witness to try to dictate to a congressional committee what our procedures for questioning him are," Nadler told reporters.

"He is supposed to show up on Thursday and we will take whatever action we have to take if he doesn't," he added.

Justice Department officials had no immediate comment on the lawmaker's remarks.

A Democratic congressional aide on Sunday said that Barr could skip the upcoming hearing because he objects to plans for an extra hour of questioning by lawmakers and committee attorneys and a closed session to discuss classified segments of U.S. Special Counsel Robert Mueller's Russia investigation report.

Nadler has subpoenaed the unredacted Mueller report and the Justice Department faces a deadline that expires on Wednesday at 10 a.m. ET to provide the full document.