US Attorney General Merrick Garland defended the Justice Department on Tuesday against what he called "repeated attacks" and conspiracy theories floated by Republican lawmakers.

"I will not be intimidated," Garland said in remarks at a hearing of the House Judiciary Committee. "And the Justice Department will not be intimidated."

Garland dismissed right-wing claims that the prosecution in New York of former Republican president Donald Trump on charges of falsifying business records was "somehow controlled by the Justice Department."

"That conspiracy theory is an attack on the judicial process itself," Garland said, noting that Trump was convicted in a state trial independently brought by the Manhattan District Attorney.

The attorney general said there has been a "long line of attacks on the Justice Department's work," including a threat by Republican lawmakers to defund special counsel Jack Smith's multipronged investigation into Trump.

"These repeated attacks on the Justice Department are unprecedented and unfounded," he said. "These attacks have not, and they will not, influence our decision-making."

Garland criticized an attempt by Republican members of the committee to hold him in contempt for the refusal to turn over audio of Democratic President Joe Biden's questioning by investigators probing his handling of classified documents.

Garland said a transcript of special counsel Robert Hur's five-hour interview with Biden was released publicly, and "releasing the audio would chill cooperation with the department in future investigations."

The attorney general condemned what he called "baseless and extremely dangerous falsehoods" being spread about the FBI's law enforcement operations and "heinous threats of violence being directed at the Justice Department's civil servants."