WASHINGTON: US Attorney General Jeff Sessions was questioned last week by the special counsel’s office investigating potential collusion between Russia and President Donald Trump’s 2016 presidential campaign, the US Justice Department said on Tuesday.

The interview marked the first time that Special Counsel Robert Mueller’s office is known to have interviewed a member of Trump’s Cabinet.

The interview with Sessions, who served as an advisor to Trump’s campaign before the president appointed him as the top US law enforcement official, is another serious development in an investigation that has hung like a cloud over Trump’s year-old presidency.

Sessions recused himself from overseeing the Russia probe last March after media outlets reported he had failed to disclose several 2016 meetings with Russia’s ambassador. His recusal paved the way for Deputy Attorney General Rod Rosenstein, the No. 2 official in the Justice Department, to appoint Mueller as special counsel in May 2017.

Reuters could not immediately learn details about what kinds of questions Sessions faced during his interview, which was first reported by the New York Times.

But his involvement in Trump’s firing of former FBI Director James Comey is likely to be one area of interest for Mueller’s team as it looks at potential obstruction of justice by the Republican president.

Ian Prior, a Justice Department spokesman, confirmed that Sessions met with Mueller’s team last week, but did not provide any additional details. An attorney representing Sessions could not immediately be reached for comment.

Trump fired Comey last May after both Sessions and Rosenstein penned a memo recommending his ouster over his prior handling of the investigation into former Secretary of State Hillary Clinton’s use of a private email server. Clinton was the Democratic presidential candidate who lost to Trump in 2016.

Trump later said he fired Comey over “this Russia thing”, a comment that raised questions about whether he was attempting to obstruct the FBI’s investigation. Mueller took over the investigation after being appointed special counsel.

Sessions’ participation in a March 31, 2016, meeting of Trump’s national security campaign advisers could also be of interest to Mueller.

At that meeting, which Sessions led, former campaign volunteer and adviser George Papadopoulos offered to help broker a meeting between Trump and Russian President Vladimir Putin.

Papadopoulos has pleaded guilty to lying to the FBI, and is now cooperating with Mueller’s ongoing investigation.

Sessions had previously testified he was unaware of any contact between campaign associates and Russians.

However, after news of Mueller’s criminal charges against Papadopoulos became public, he later testified before Congress that he did now recall the meeting. In that testimony, he said he pushed back against Papadopoulos’ suggestion of a Putin meeting.

Trump this month refused to commit to being interviewed by Mueller, saying “I’ll speak to attorneys” about the matter and that “there was absolutely no collusion”. US intelligence agencies have concluded that Russia interfered in the 2016 campaign using hacking and propaganda to attempt to tilt the race in favor of Trump. Russia has denied it.