Mr. Barr portrayed his requests as an effort to aid Mr. Durham. The attorney general said that foreign governments had asked about the scope and nature of the Durham investigation and how the Justice Department would handle confidential information. He said he fielded those questions to help Mr. Durham, not to manage his investigation.

“I initially discussed these matters with those countries and introduced them to John Durham and established a channel by which Mr. Durham can obtain assistance from those countries,” Mr. Barr said, emphasizing that Mr. Durham was running his own investigation.

Mr. Durham, the United States attorney in Connecticut and a veteran of politically charged investigations, and his investigators have interviewed nearly 30 former and current F.B.I. and intelligence officials. They have asked whether any of the officials who investigated Russia’s 2016 election interference and possible links to the Trump campaign exhibited anti-Trump bias.

The Durham team has homed in on aspects of the Russia investigation that Mr. Trump and his allies have long attacked, including the decisions surrounding a secret application to wiretap Carter Page, a Trump campaign adviser who was suspected of being groomed to be a Russian asset. Mr. Page has denied those allegations.

To conduct a thorough review of an investigation, however, Mr. Durham would have to run down all leads, even those that earlier investigations dismissed.

Mr. Barr defended the Durham investigation as “thorough and fair,” adding that Mr. Durham was “making great progress” but declining to detail it.

He also extolled the F.B.I. director, Christopher A. Wray, and the F.B.I. agents whom Mr. Durham has interviewed, for their “outstanding support and responsiveness.” The praise was a sign that Mr. Barr was trying to maintain a good relationship with the F.B.I. even as the Justice Department scrutinizes its most politically consequential investigation in a generation.