WASHINGTON • Former CIA directors and another half dozen of America's most senior spies have issued an unprecedented condemnation of President Donald Trump, after his decision to blacklist their colleague John Brennan.

In a statement, former Central Intelligence Agency bosses appointed by Republican and Democratic presidents - including Mr Robert Gates, Mr George Tenet, Mr Porter Goss, Mr Leon Panetta and retired general David Petraeus - denounced Mr Trump's decision to strip Mr Brennan of his security clearance.

Dozens of other former spies signalled their support for the statement, which read: "The President's action regarding John Brennan and the threats of similar action against other former officials have nothing to do with who should and should not hold security clearances - and everything to do with an attempt to stifle free speech."

Describing Mr Trump's move as "inappropriate and deeply regrettable", they insisted "we have never before seen the approval or removal of security clearances used as a political tool, as was done in this case".

Two of those who signed the statement - former director of national intelligence James Clapper and former CIA director Michael Hayden - are, according to Mr Trump, on a list of people who could lose their clearance.

Former officials often retain security clearance after leaving office to allow their successors to consult them on issues of the day.

The White House said Mr Brennan - a notable Trump critic - had been stripped of clearance due to his "erratic" behaviour.

But in an interview with The Wall Street Journal, Mr Trump admitted that his decision on Mr Brennan's clearance was linked to the ongoing federal probe into possible collusion between his campaign and Russia to influence the 2016 election.

Mr Trump's actions have been widely condemned, including by respected former admiral William McRaven, the commander of the US Navy Seal raid that killed Osama bin Laden.

AGENCE FRANCE-PRESSE