SIR John Chilcot has repeatedly rejected offers of assistance from the Government to speed up his long-awaited report into the British role in the war in Iraq.

The head of the civil service Sir Jeremy Heywood told MPs on the public administration and constitutional affairs committee that his offer of legal resources had been turned down by the inquiry chair.

Last month Sir John told the Prime Minister that he did not known when the inquiry would publish its report. David Cameron replied to say he was “fast losing patience”.

The wide-ranging inquiry into the Iraq war spoke to hundreds of witnesses. It is the process of ‘‘Maxwellisation’’ that appears to be slowing publication down.

Maxwellisation allows anyone the report may be critical of to see a copy and challenge findings before it is published.

Although not officially confirmed it is believed there may be 40 people who have either not yet responded or who have challenged Sir John’s report.

Sir Jeremy said that other than offer extra resources, there was nothing he or the Government could do to speed up the release of the report.

Answering Labour MP Paul Flynn Sir Jeremy said: “I’m not washing my hands of it. It is an independent inquiry, the timetable is not in my hands.

“I have repeatedly offered to Sir John extra resources on behalf of the prime minister; extra legal resources and so on. At the Prime Minister’s request I saw him again recently. We had a private meeting at which I repeated that request, obviously.”

Sir John told the Cabinet Secretary that no extra resources were needed and the inquiry team were working as fast as they were able.

Sir Jeremy continued: “I just know that John Chilcot will complete this report as soon as he possibly can.

‘‘He is as aware as everybody else is about the importance of getting this done and quickly. Everybody shares your frustration, from the Prime Minister downwards – including Sir John Chilcot – about how long this has taken.

“I don’t think anybody is deliberately trying to slow down the inquiry.”

There would, Sir Jeremy promised, be a “long, hard look” into the length of time taken by the inquiry, but in the meantime “the inquiry needs to just get its head down and complete its work.”

It has been 1630 days since the inquiry started. The length of time taken has seen the coast soar to over £10 million.

SNP defence spokesman Brendan O’Hara said the decision to turn down offers of help was “perverse”.

O’Hara said: ‘‘This is an extraordinary revelation. It is now six long years since the Inquiry led by Sir John Chilcot started to take evidence from witnesses involved in the period leading up to the illegal invasion of Iraq, at a cost of £10 million – to decline the offer of more resources to help come to a conclusion seems perverse.

“We need to get to the bottom of this calamitous war and its consequences.

“This inquiry needs to be published in full – and as a matter of urgency.”