Donald Trump revokes security clearance of critic and former CIA chief John Brennan

Donald Trump has revoked the security clearance of former CIA director John Brennan, denying the US leader’s critic any access to sensitive information.

President Trump denounced Mr Brennan’s criticism and spoke of the “risks posed by his erratic conduct and behaviour” as the decision was announced on Wednesday.

Responding to the move, Mr Brennan said the move was part of the president’s broader efforts to “suppress freedom of speech and punish critics”.

"It should gravely worry all Americans, including intelligence professionals, about the cost of speaking out,” he added in a furious tweet.

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

Mr Trump also threatened to pull the clearances of a handful of individuals, including former top intelligence and law enforcement officials, as well as a current member of the Justice Department.

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

The president described his own action as fulfilling his "constitutional responsibility to protect the nation's classified information."

But critics said the move marked an unprecedented politicisation of the federal government's security clearance process.