Justice Department Sarah Isgur Flores told the New York Times that Sessions met with Mueller's office as part of the investigation into alleged Russian interference in the 2016 election and reported collusion between Moscow and the Trump campaign.
READ MORE: US Lawmaker Calls to Recover Anti-Trump Messages by FBI Agents in Russia Probe
Sessions' interview marks the first time a member of Trump's cabinet has been questioned by the special counsel's office.
Mueller’s investigation was launched in May to look into evidence that Russia allegedly attempted to influence the results of the 2016 US presidential election.
Trump has denied allegations of collusion with Moscow. Russia, for its part, has repeatedly refuted accusations it interfered in the 2016 US presidential election and denied it was involved in a collusion to sway the vote.