David Cameron faces calls to sack the chairman of the Iraq War after it emerged it will not be published for at least another year.

Ministers face calls for an urgent statement to Parliament on the future of the inquiry, as some urged David Cameron to pull the plug. Lord Morris of Aberavon, a former Attorney General, demanded that the Prime Minister consider sacking Sir John Chilcot.

By the end of this year the inquiry will have lasted for longer than British combat troops were fighting in Iraq.

The inquiry headed by Sir John Chilcot has already lasted six years and cost £10million, and is now set to be delayed for another year

The inquiry headed by Sir John Chilcot has already lasted six years and cost £10million.

But a source close to the inquiry told the Independent on Sunday it is 'unlikely to be published for another year at least'.

In January, Sir John wrote to Mr Cameron insisting 'very substantial progress' had been made in completing his report but admitting that it will not be possible to publish his report ahead of the general election in May.

Now it could be at least another 12 months before it is made public – if ever. Ex-Labour Attorney General Lord Morris is pressing the Prime Minister to assess 'the case for discharging the Chairman and members of the Chilcot inquiry, and inviting the Cabinet Secretary to set out a mechanism for an interim report to be produced on the basis of the evidence gathered'.

Tony Blair – who is set to be criticised in the report - has repeatedly denied being responsible for the delays

CAREER DIPLOMAT WHO KEEPS DELAYING IRAQ WAR REPORT Sir John Chilcot, the former Whitehall mandarin charged with heading the Iraq investigation, sat on the 'whitewash' Butler Inquiry into the use of intelligence in the run-up to the conflict. Sir John was one of the leading members of the inquiry which exonerated the Blair government for 'sexing up' the case for war. His appointment by Gordon Brown raised fears in Westminster of the latest in a long line of establishment cover-ups - following Butler and the Hutton report into the death of Dr David Kelly. A career diplomat, Sir John, is an intelligence expert who was principal private secretary to William Whitelaw during his time as Tory Home Secretary and also spent seven years as top civil servant in the Northern Ireland office. At the time of his appointment, one colleague described him as 'the best Home Office type of mandarin, really quite outstanding of his generation, an immensely subtle mind'. Sir John headed the Government's seven-month inquiry into intercept evidence, which led to Gordon Brown accepting the principle of its use as evidence in court trials. Advertisement

The suggestion of a fresh delay to its publication today provoked a furious reaction from SNP Westminster Leader Angus Robertson.

He said: 'We must have a parliamentary statement on the status of the Chilcot inquiry in light of these troubling reports.

'For the Chilcot report to be subject to yet more delays is completely unacceptable, and will be greeted with dismay by the hundreds of thousands of people whose lives were affected by the Iraq war.

'This inquiry needs to be published in full - and as a matter of urgency. Abandoning it as suggested by Lord Morris would be wholly unacceptable.

'The Iraq war was a foreign policy disaster whose ramifications are still being felt today. Answers are long overdue, and the continued delays to the publication of this report are a democratic outrage.'

Sir John was asked to investigate the Iraq war by Gordon Brown in 2009 and last took evidence from a witness almost three years ago.

Responses and objections from the many parties expected to be criticised, who have been sent draft conclusions, are the main reason for the delay, sources say.

Tony Blair – who is set to be criticised in the rpoert - has repeatedly denied being responsible for the delays.

He said in January: ''Just to state absolutely and emphatically, this is not to do with me, or as far as I'm aware any other witness.'

Commons Leader Chris Grayling last week made clear the growing impatience in government at the delays.

He told MPs: 'All of us in government would dearly like to see the Chilcot report published, but as it is an independent report it is out of our hands.

'It is in the interests of the country to get the report published, to see the full the details of what it says, to learn any lessons and to ensure that mistakes are not made in future.'