Attorney General Jeff Sessions said Thursday that he wouldn't rule out appointing a special prosecutor to investigate the Justice Department under former President Obama.

"I'm going to do everything I possibly can to restore the independence and professionalism of the Department of Justice," Sessions told conservative radio host Hugh Hewitt. "So we would have to consider whether or not some outside special counsel is needed.

"Generally, a good review of that internally is the first step before any such decision is made."

Hewitt had asked Sessions about whether outside counsel was needed to probe a series of Obama-era controversies that sparked criticism from conservatives. Under Obama, the department was attacked by Republicans for, among other issues, its handling of the probe into former Secretary of State Hillary Clinton's use of a private email server and investigations into local police departments.

President Trump also claimed last weekend, without offering any evidence, that Obama ordered officials to wiretap Trump Tower during last year's presidential race.

Of particular concern, Sessions said, was the Justice Department's handling of an investigation into whether the IRS improperly targeted conservative groups for investigation. The Justice Department closed the probe without filing any charges against the agency, citing a lack of evidence of intended wrongdoing.

"That circumstance raised a lot of questions in my mind, and when I was in the Senate," Sessions said. "So it is a matter of real concern to me."

Talk of a special prosecutor to investigate the Obama Justice Department comes amid calls for a separate special prosecutor to investigate links Trump's associates and the Russian government.