(CNN) President Donald Trump lashed out at former CIA Director John Brennan on Saturday, claiming he made mistakes during his time at the CIA and calling him a "loudmouth, partisan, political hack."

"Has anyone looked at the mistakes that John Brennan made while serving as CIA director? He will go down as easily the WORST in history & since getting out, he has become nothing less than a loudmouth, partisan, political hack who cannot be trusted with the secrets to our country!" Trump wrote on Twitter.

Has anyone looked at the mistakes that John Brennan made while serving as CIA Director? He will go down as easily the WORST in history & since getting out, he has become nothing less than a loudmouth, partisan, political hack who cannot be trusted with the secrets to our country! — Donald J. Trump (@realDonaldTrump) August 18, 2018

Trump did not say what the claimed mistakes were. The White House announced on Wednesday that Trump would revoke Brennan's security clearance. In a statement, Trump said Brennan "has recently leveraged his status as a former high-ranking official with access to highly sensitive information to make a series of unfounded and outrageous allegations -- wild outbursts on the internet and television -- about this Administration." The statement added that the "recent conduct characterized by increasingly frenzied commentary is wholly inconsistent with access to the nation's most closely held secrets."

Trump's attack on Brennan comes a day after the former CIA director accused the President in an MSNBC interview of stripping his security clearance as part of a "public relations strategy." Brennan was reacting to a report in The Washington Post on Friday that said the decision to revoke his security clearance had been finalized in order to switch the news cycle's focus from former White House aide Omarosa Manigault Newman's new book, "Unhinged," which contains critical passages about Trump.

"The fact that he's using a security clearance of a former CIA director as a pawn in his public relations strategy I think is just so reflective of somebody who, quite frankly, I don't want to use this term maybe, but he's drunk on power. He really is, and I think he's abusing the powers of that office," Brennan told MSNBC's Rachel Maddow in the interview.