A Harvard dean on Friday revoked an invitation for convicted US intelligence leaker Chelsea Manning to be a visiting fellow at the prestigious university following sharp criticism over the invite.

Manning however will still speak to Harvard students, but not be considered a visiting fellow, the dean of the Harvard Kennedy School said in a statement.

"I see more clearly now that many people view a Visiting Fellow title as an honorific," Dean Douglas Elmendorf wrote.

"Therefore, we are withdrawing the invitation to her to serve as a Visiting Fellow —- and the perceived honor that it implies to some people —- while maintaining the invitation for her to spend a day at the Kennedy School and speak in the (School) Forum."

CIA director Mike Pompeo pulled out of a Harvard forum and former acting director Mike Morrell quit the university Thursday to protest Manning's appointment as a visiting fellow.

Pompeo, who was scheduled to speak late Thursday at the Kennedy School of Government, canceled at the last minute following news of Manning's speaking engagement.

Labeling Manning an "American traitor," Pompeo said in a statement that his conscience would not allow him to "betray the trust" of the Central Intelligence Agency staff by appearing to support Harvard's decision by joining the event.

- Manning as visiting fellow a 'mistake' -

"Ms Manning betrayed her country and was found guilty of 17 serious crimes for leaking classified information to Wikileaks," he said in a statement.

"Ms Manning stands against everything the brave men and women I serve alongside stand for."

Pompeo, who attended Harvard Law School, said it was "shameful" that Harvard gave Manning's actions its "stamp of approval."

Earlier Morrell said he was stepping down as a senior fellow at The Belfer Center, part of the Kennedy School, for the same reason.

Elmendorf said that inviting Manning to be a visiting fellow "was a mistake, for which I accept responsibility."

Manning was one of several people, including former White House Press Secretary Sean Spicer, and Hillary Clinton campaign manager Robby Mook, named as Kennedy School visiting fellows Wednesday for the 2017-2018 year.

Manning, then known as Bradley Manning, was convicted of espionage and other charges in 2013 for leaking hundreds of thousands of secret US diplomatic communications and other documents to WikiLeaks. 

Sentenced to 35 years in prison, the former army intelligence analyst had her sentence commuted in May by President Barack Obama to seven years dating to her 2010 arrest and she was freed. While in prison Manning transitioned from male to female.