LONDON (AP) — The man leading an inquiry into Britain's contentious role in the Iraq war said Wednesday that he can't estimate when his long-delayed report might be published.

John Chilcot was pressed by a committee of lawmakers about the publication date for his report. He began his inquiry in 2009 and heard from the final witness in 2011.

Last month, Chilcot conceded that his report wouldn't be published before Britain's national election in May.

On Wednesday, he said "it's impossible to say" when it would be ready and he didn't want to raise false hopes.

The release was initially stalled by wrangling over the inclusion of classified material, including conversations between then-Prime Minister Tony Blair and President George W. Bush.

It is being further delayed to give individuals it mentions a chance to respond.

Chilcot also told the lawmakers that a member of his five-person inquiry panel, historian Martin Gilbert, died on Tuesday.

Chilcot, a former senior civil servant, said despite the delays he was determined to produce a report that "gives the government, Parliament, the public, and particularly all those who have been deeply affected by events in Iraq, the answers they deserve."

"All of us are determined to get this thing done," he said. "None of us thought it would take this long."

Britain's participation in the 2003 U.S.-led invasion was deeply controversial at the time, and became more so when no trace of Saddam Hussein's alleged weapons of mass destruction were found.

Between 2003 and the British withdrawal in 2009, 179 U.K. troops died in Iraq.