TONY Blair was not “straight with the nation” and relied on “belief” rather than fact in the run-up to the Iraq War, Sir John Chilcot has claimed.

In an interview with the BBC to mark the one year anniversary of his report into the 2003 conflict, Sir John said the testimony of the Labour leader to his inquiry had, at best, been “emotionally truthful”.

The SNP called the remarks “damning” and demanded Blair be held accountable.

Chilcot was asked outright by BBC political editor Laura Kuenssberg if Blair was as truthful with him and the public as he should have been.

“Any prime minister taking a country into war has got to be straight with the nation and carry it, so far as possible, with him or her,” the former top civil servant replied.

“I don’t believe that was the case in the Iraq instance.”

The Chilcot Report was finally released last year, after seven years of investigation, at a cost of £13 million to the tax payer.

According to the report, Iraqi dictator Saddam Hussein posed “no imminent threat’’ to the UK at the time of the US-UK led invasion, and the war was fought on the basis of “flawed” intelligence.

At the time Blair had told MPs Saddam was developing weapons of mass destruction that could be deployed within 45 minutes.

While giving evidence to the inquiry, Blair denied he had taken the country to war on the basis of a “lie” over Saddam’s supposed weapons of mass destruction.

Asked if he felt Blair had given the fullest version of events to the inquiry, Chilcot said: “I think he gave an – what was – I hesitate to say this, rather, but I think it was, from his perspective and standpoint, emotionally truthful and I think that came out also in his press conference after the launch statement.

“I think he was under – as you said just now – very great emotional pressure during those sessions ... He was suffering. He was deeply engaged. Now in that state of mind and mood you fall back on your instinctive skills and reactions, I think.”

Asked if Blair had “exaggerated”, Chilcot replied: “He found – I don’t know whether consciously or not – a verbal formula in the dossier and his foreword to it.

“He said – and used it again later – ‘I believe the assessed intelligence shows beyond doubt.’ Pinning it on my belief, not on the fact, what the assessed intelligence said.”

Chilcot added: “Tony Blair is always and ever an advocate.

“He makes the most persuasive case he can.

“Not departing from the truth but persuasion is everything. Advocacy for my position, my Blair position.”

Asked if Blair had manipulated the evidence, Chilcot replied saying the Prime Minister had been given bad information at key times.

“I’m declining the word ‘manipulate’. Using as best he could.

“But it’s only fair to him to say that on the very eve of the invasion he asked the then chair of the Joint Intelligence Committee, can you tell me beyond any reasonable doubt that Saddam has weapons of mass destruction.

“To which the answer was, ‘yes I can’.”

Blair’s office said the BBC misrepresented what Chilcot had said in the interview, claiming the full transcript clearly showed that the former Whitehall mandarin did not think the former Prime Minister had “departed from the truth”.

The SNP’s Stephen Gethins said: “There must be accountability for the actions that led to the UK’s biggest foreign policy mistake in recent history.

“A mistake that we continue to live with as do millions of Iraqis who have seen their country blighted by terror and conflict.”

He added: “We know that long before parliament formally voted on whether or not to go to war in Iraq, Tony Blair had told George Bush – ‘I will be with you whatever’.”

Menzies Campbell, who opposed the war as foreign affairs spokesman of the LibDems at time, said: “In truth, Mr Blair’s decision was fundamentally wrong.

“A bad decision, even if made in good faith, is still a bad decision.”

Researchers estimate that, of the approximately 376,000 deaths in Iraq between 2003 and 2011, 184,000 were attributed to the conflict, and 132,000 to war-related violence.