President Donald Trump's chief of staff, John Kelly, answered questions from special counsel Robert Mueller's team of investigators as part of a probe into potential obstruction of justice by Trump, according to new reports.

A person familiar with the situation told NBC News that Kelly was asked by Mueller's team about a coversation he witnessed between Trump and then-White House Counsel Don McGahn.

The president allegedly asked McGahn to refute a New York Times article in March that reported McGahn had been ordered to fired Mueller.

CNN first reported Friday that Kelly, who reportedly is on the verge of leaving the White House, answered a "narrow set of questions" from Mueller's investigators. A source who spoke with NBC News confirmed that description of the scope of the questions.

That sit-down came after White House lawyers first objected to Kelly being interviewed.

CNN reported: "The Mueller questions to Kelly centered on a narrow set of issues in the investigation of potential obstruction of justice, chiefly Kelly's recollection of an episode that took place after new reporting emerged about how the President had tried to fire Mueller."