The Chilcot Inquiry into the 2003 Iraq War will cost taxpayers £10m and will not be delivered until after the 2015 General Election, according to a government whip.
Lord Wallace of Saltaire, answering a question in the House of Lords, told peers that the investigation led by Sir John Chilcot has so far cost £9m ($14.4m, €11.5m).
The inquiry was opened in 2009 and was expected to report its findings three years ago, but Wallace said it would "inappropriate" for the report to be published in the run up to the 2015 General Election next may.
The Liberal Democrat peer also compared the costings of the investigation to the amount spent on the Saville Inquiry into the Bloody Sunday shootings in Northern Ireland, which totalled £195m.
But the former Foreign Secretary William Hague has called for the report to be published before the election.
"I'm not in control of the timing of the release of the report, certainly ministers hope it will available in the not too distant future," the Conservative told MPs in October.
"I hope it reports before the general election but I'm not in control of that."
The inquiry looked into the invasion of Iraq in 2003 and interviewed former Prime Ministers Tony Blair and Gordon Brown as well as military commanders and diplomats.
The investigation had a broad terms of reference, with the ability to consider the UK's involvement in Iraq between mid-2001 and July 2009.