Sir John Chilcot completed his public hearings into the Iraq war in 2011 but the report has since been delayed by disagreements over whether or not private discussions between Tony Blair and George W Bush should be made public.
The Prime Minister said: "It's frustrating but it's not in my gift. This is an independent inquiry. I want to see it published soon; my understanding is that they will be able to publish before the end of the year."
"The public wants to see the answers of the inquiry and we shouldn't have to wait too much longer." The Deputy Prime Minister also accepted the four-year delay was "very frustrating", revealing that he had asked Sir Jeremy Heywood, the Cabinet Secretary, to ensure all Whitehall departments were co-operating on all outstanding issues about declassified information.
Asked if they were not co-operating, Mr Clegg replied: "Its' just incredibly lengthy and complicated. There are so many documents, so much to-ing and fro-ing. It's really important it should be published.
"It should and can be published by the end of the year."