John Brennan has called Donald Trump’s repeated denials that his campaign colluded with Russia during the 2016 election “hogwash” and accused the president of revoking his security clearance as part of a “desperate” attempt to interfere with the special counsel’s investigation.

The war of words between the former CIA director and the president escalated on Thursday, as Brennan hit back after being stripped of his security clearance by the White House the previous day – an unprecedented presidential intervention that has prompted widespread criticism. A statement from Trump said he had taken the step due to Brennan’s “erratic conduct and behavior”.

Brennan, who was CIA director from 2013 to 2017 during the Obama administration, has stepped up his criticism of Trump in recent months.

Writing in an article for the New York Times published on Thursday, Brennan described the decision as “politically motivated” and “an attempt to scare into silence others who might dare to challenge him”.

“Mr Trump’s claims of no collusion [with Russia] are, in a word, hogwash,” he wrote.

He added that “it is critically important that the special counsel, Robert Mueller, and his team of investigators be allowed to complete their work without interference – from Mr Trump or anyone else – so that all Americans can get the answers they so rightly deserve”.

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

On Wednesday night, Trump shared a variety of quotes from Fox News pundits bashing Brennan and the Obama administration on his Twitter feed, including one describing the former CIA director as “a stain on the country”.

Trump also admitted there was a link between stripping Brennan of his security clearance and the special counsel investigation.

In an interview with the Wall Street Journal, Trump said: “I call it the rigged witch-hunt. [It] is a sham. And these people led it. So I think it’s something that had to be done.”

The move comes as the White House has been rocked by allegations against the president by former aide Omarosa Manigault Newman, including the claim that an audio tape exists of Trump using “the N-word”, and has been interpreted by some critics as an attempt to change the conversation.

“John Brennan is a stain on the Country, we deserve better than this.” Former Secret Service Agent and author of new book, “Spygate, the Attempted Sabotage of Donald J. Trump,” Dan Bongino. Thank you Dan, and good luck with the book! — Donald J. Trump (@realDonaldTrump) August 16, 2018

Democrats, and some Republicans, denounced the president’s move, with the leading Democrat Nancy Pelosi calling it a “stunning abuse of power”.

Speaking from a prepared statement on Wednesday, the White House press secretary, Sarah Sanders, alleged that Brennan had “leveraged his status as a former high-ranking official with access to highly sensitive info to make a series of unfounded and outrageous allegations, wild outbursts on internet and television about this administration”.

She added that Brennan’s “lying and recent conduct, characterized by increasingly frenzied commentary, is wholly inconsistent with access to the nation’s most closely held secrets”. There was no reference to the Russia investigation in the statement.

Sanders also listed nine other national security figures whose security clearances were under review. All but one no longer serve in the United States government and it includes several noteworthy Trump adversaries, including the former FBI director James Comey, former director of national intelligence James Clapper and former acting attorney general Sally Yates.

Clapper called Trump’s actions “unprecedented”, but told CNN he would not stop speaking out.

Those listed also include former CIA director Michael Hayden, former national security adviser Susan Rice, Trump’s former deputy FBI director Andrew McCabe and fired FBI agent Peter Strzok, who was removed from the Russia investigation over anti-Trump text messages.

Former FBI lawyer Lisa Page, with whom Strzok exchanged messages, has also been listed, as well as senior justice department official Bruce Ohr, whom Trump recently accused on Twitter of “helping disgraced Christopher Steele ‘find dirt on Trump’”.

Ohr was friends with Steele, the former British intelligence officer commissioned by an American political research firm to explore Trump’s alleged ties with the Russian government. Ohr is the only current government employee on the list.

At least two of the former officials, Comey and McCabe, do not currently have security clearances, and none of the eight receive intelligence briefings. Trump’s apparent concern is that their former status gives special weight to their statements, both at home and abroad.

Democrats called it an “enemies list”, a reference to the Nixon White House, which kept a list of President Richard Nixon’s political opponents to be targeted with punitive measures.

Sanders insisted the White House was not only targeting Trump critics. But Trump did not order a review of the clearance held by former national security adviser Mike Flynn, who was fired from the White House for lying to Vice-President Mike Pence about his conversations with Russian officials and later pleaded guilty to lying to the FBI.

In his article on Thursday, Brennan claimed that the question was not if collusion took place, but whether it “constituted criminally liable conspiracy, whether obstruction of justice occurred to cover up any collusion or conspiracy, and how many members of ‘Trump Incorporated’” had “attempted to defraud the government by laundering and concealing the movement of money into their pockets”.

The former CIA director has long been a vocal critic of Trump. Recently, he suggested that Trump’s behavior in his joint press conference with Vladimir Putin in Helsinki rose to the level of an impeachable offense.

Brennan tweeted at the time: “Donald Trump’s press conference performance in Helsinki rises to & exceeds the threshold of ‘high crimes & misdemeanors.’ It was nothing short of treasonous. Not only were Trump’s comments imbecilic, he is wholly in the pocket of Putin. Republican Patriots: Where are you???”