Former CIA director John Brennan has launched a blistering attack on Donald Trump, branding the US President “unstable, inept, inexperienced and unethical”.

Mr Brennan said he was “moving into the realm of deep worry and concern” as the consequences of Mr Trump’s ill-preparedness for the office were becoming clear.

In an interview with MSNBC’s Deadline White House programme, Mr Brennan claimed the President was not dealing with key issues facing the country and problems were now “coming to roost”.

“It is no secret to anybody that Donald Trump was ill-prepared and inexperienced in terms of dealing with matters that a head of state needs to deal with,” he said.

“I think this is now coming to roost and I am really worried particularly the reports of the last couple of days, I think he must be feeling the pressure.

“I had been very angry at Donald Trump for the things he said and the things he did - I am now moving into the realm of deep worry and concern, our country needs strong leadership.

“Our country needs confidence that we are going to be able to deal with Mr Putin who is once again flexing his muscles on the military front, that we can deal with North Korea.

“If we have somebody in the Oval Office who is unstable, inept, inexperienced and also unethical, we really have rough waters ahead.”

The interview is not the first time the ex-CIA boss, who served in senior security roles under both George W Bush and Barack Obama, has publicly criticised Mr Trump.

Just five days before his inauguration, Mr Brennan warned the incoming President did not understand the threat Russia posed to the United States.

In July last year, the former intelligence chief claimed America was a “nation in crisis”, while discussing Mr Trump’s handling of Russia.

Mr Brennan also offered a grim prediction for the direction of the United States during Mr Trump’s presidency.

“I do think it’s unfortunately going to get a bit more painful, a bit worse before it gets better,” he added.

“I do hope we are going to be able to get through this very, very difficult chapter in our history without incurring damage that could be long-lasting.”