US President Donald Trump abruptly revoked former-CIA Director John Brennan’s security clearance and warned he may do the same to other former officials.

A statement read by the White House press secretary, Sarah Huckabee Sanders, accused Brennan of having “leveraged” access to highly sensitive information to make a series of “unfounded and outrageous” allegations.

“Mr Brennan’s lying and recent conduct characterized by increasingly frenzied commentary is wholly inconsistent with access to the nations’ most closely held secrets,” the statement attributed to Trump said.

Brennan, who has been a vocal critic of the US president over his alleged ties to the Kremlin, said Trump was trying to “suppress freedom of speech and punish critics”.

“It should gravely worry all Americans, including intelligence professionals, about the cost of speaking out,” he said on Twitter.

“My principles are worth far more than clearances. I will not relent.”

Brennan had earlier called Trump’s performance at a press conference with Russian President Vladimir Putin in Finland last month “nothing short of treasonous.”

“I’ve seen this type of behaviour and actions on the part of foreign tyrants and despots and autocrats for many, many years during my CIA and national security career. I never, ever thought that I would see it here in the United States,” Brennan said on Wednesday.

Brennan said he had not heard from the CIA or the Office of the Director of National Intelligence that his security clearance was being revoked, but learned of the move when the White House announced it.

Former CIA directors and other top national security officials are typically allowed to keep their clearances, at least for some period, so that they can be in a position to advise their successors.

Trump has also threatened to remove clearances from a handful of individuals, including former top intelligence officials, as well as a current member of the Department of Justice.

All are critics of the president or are people who Trump appears to believe are against him.

Democrats, and even some Republicans, lined up to denounce the president’s move, with House Minority Leader Nancy Pelosi slamming it as a “stunning abuse of power.”