Washington (CNN) Former independent counsel Ken Starr says special counsel Robert Mueller should look into whether President Donald Trump lied to the public about not trying to fire him.

"If the reports are correct that President Trump sought to have Mueller fired, then his public denial would be false. So would that be grounds for impeachment?" ABC's "This Week" anchor Martha Raddatz asked Starr on Sunday

"I think lying to the American people is a serious issue that has to be explored. I take lying to the American people very, very seriously," Starr said, adding, "So absolutely, I think that is something Bob Mueller should look at."

When prosecuting then-President Bill Clinton, Starr used Clinton's public denials of an affair with Monica Lewinsky as grounds for impeachment when he served as independent counsel in the 1990s.

Trump called for Mueller's firing last June, according to one person familiar with the matter. White House counsel Don McGahn refused to order the Justice Department to fire Mueller because he disagreed with the President's reasoning, the source said.

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