Twelve former intelligence officials in the United States alleged on Thursday that the withdrawal of the security access of a former Central Intelligence Agency director by the White House was a “political” decision.

Trump had cited “erratic conduct and behaviour” while revoking John Brennan’s security access on Wednesday. Brennan has been one of the vocal critics of the Trump administration and had called last month’s summit between Trump and his Russian counterpart Vladimir Putin in Helsinki “nothing short of treasonous”.

The twelve former officials who issued a statement in Brennan’s support included 11 former CIA directors and deputy directors and one former director of national intelligence. They said the signal sent by the White House’s decision was “deeply regrettable” and “inappropriate”.

“We feel compelled to respond in the wake of the ill-considered and unprecedented remarks and actions by the White House,” said their statement. “We have never before seen the approval or removal of security clearances used as a political tool, as was done in this case.”

They said the decision was an attempt to “stifle free speech” and “a signal to other former and current officials”. “You don’t have to agree with what John Brennan says (and, again, not all of us do) to agree with his right to say it, subject to his obligation to protect classified information.”

While announcing the decision on Wednesday, White House Press Secretary Sarah Sanders had said Brennan’s “lying and recent conduct, characterised by increasingly frenzied commentary, is wholly inconsistent with access to the nation’s most closely held secrets”. Brennan had called the action part of a broader effort to suppress freedom of speech and punish critics.

“It should gravely worry all Americans, including intelligence professionals, about the cost of speaking out,” Brennan had said. “My principles are worth far more than clearances. I will not relent.”

Last year, Brennan said an investigation into possible collusion between officials of the Trump presidential campaign and Russia during the US elections in 2016 had been “well-founded”. Trump has repeatedly denied the claim and called it a “witch hunt”.