DAVID Cameron should have insisted on a date for publication of the Chilcot Inquiry report into the Iraq war “over a year ago”, the SNP have argued, after it was revealed the Prime Minister is now to demand one from Sir John.

Six years on from the start of the investigation into the causes of the 2003 invasion, which has cost the taxpayer £10 million, the continuing delay in publishing the Chilcot report has been put down to the process of so-called Maxwellisation, where people criticised in it have the right to reply. After yet more delays, the report is now not expected before the end of the year.

However, Mr Cameron’s patience appears to be wearing very thin as he has made clear he now wants a “timetable...pretty soon”, noting how the delay was heartbreaking for the families of soldiers, who had died in the conflict.

“For their sake, as well as for the sake of the public, we’ve got to get on with this. More important than anything is thinking of the parents who lost loved ones in Iraq," said the PM.

But Alex Salmond for the SNP noted how previously Mr Cameron had made clear he was in no position to order the publication of the Chilcot report.

"The Iraq war was a foreign policy catastrophe - the greatest and most disastrous for at least half a century,” declared the former First Minister, pointing out how the appalling ramifications were still being felt and would be for years into the future.

"The Chilcot Inquiry was demanded because people wanted answers; six years and £10 million later, we still have nothing. Hundreds of thousands of people were affected by the illegal war and they are due an answer. It was overdue six years ago and the fact that there is still no answer is completely unacceptable,” said Mr Salmond.

The MP for Gordon claimed the question for the Prime Minister now was that if he were now able to “demand” the publication date, why had he not done it sooner.

"The report has been plagued by continuous delays yet David Cameron has claimed he has been helpless during this entire process but only now says he will act. Answers are long, long overdue,” declared the ex-party leader.

Mr Salmond added: "It should be remembered that Cameron himself voted for the war in 2003. He has a moral obligation to get to the bottom of the reasons for this disastrous conflict a full twelve years later."

The SNP’s call on Chilcot follows the suggestion from Jeremy Corbyn, the Labour leadership candidate, that Tony Blair should stand trial on charges of war crimes if the evidence suggested he had broken international law over the war in Iraq.

In 2004, a cross-party group of MPs sought to impeach the former PM over the invasion. These included Mr Salmond, George Galloway, the former Respect MP, and Boris Johnson, the Conservative MP and Mayor of London, as well as novelist Frederick Forsyth, musician Brian Eno and the late author Iain Banks.