David Cameron has told Iraq Inquiry chairman Sir John Chilcot to "get on with it" and said delays to the long-awaited report into the war were "immensely frustrating".
The Prime Minister admitted he was powerless to intervene in the independent inquiry but said the parents of soldiers killed in the conflict wanted answers before the end of their own lives.
Mr Cameron said Sir John has had "plenty of time" for his work and challenged him to set a date for the report's publication.
Families of soldiers killed in the Iraq War have threatened legal action if the Chilcot Inquiry is not published by the end of the year.
Much of the anger is focused on the ongoing "Maxwellisation" process, which gives the opportunity to individuals facing possible criticism in the report to respond and is holding up publication.
Mr Cameron told BBC Radio 4's Today programme: "It is immensely frustrating. People listening to this will think 'why on earth can't the Prime Minister order this thing to be published?'. I can't. It's an independent inquiry, it has be that way."
He added: "I feel it not just because the politicians want to see this, but actually you meet mothers and fathers of those who died in Iraq who want to know the answers, and want to know before they reach the end of their lives.
"So they are immensely frustrated and I share their frustration."
Although Sir John has said the Maxwellisation process is behind the delays, Mr Cameron indicated that he thought it was time to move forward.
Asked why the report was delayed he said: "I think the answer to the question the inquiry has given is that it has taken time for those people being criticised by the report to receive those criticisms, respond to those criticism and for the inquiry team to take that into account.
"That is the inquiry's answer, you can ask them.
"My argument would be, 'you have had plenty of time now, you have got to get on with it, set a date for publication and let's put this past us'."
The Government has offered "any more resources that are needed" to Sir John, Mr Cameron added.