Tony Blair faces another public grilling about his costly decision to invade Iraq after he was recalled by the official inquiry into the war.
The former Prime Minister will answer more questions about the UK's involvement in the conflict when he returns to give evidence to the Chilcot Inquiry early next year.
Other key Labour government figures involved in ruling on the legality of the war have also been asked to provide further information for the five-strong Iraq Inquiry panel.
Ex-Foreign Secretary Jack Straw will appear in person again and former Attorney General Lord Goldsmith will provide extra written evidence.
Admiral Lord Boyce, chief of the defence staff from 2001 to 2003, and Lord Turnbull, cabinet secretary from 2002 to 2005, are also being recalled.
The inquiry will hear evidence for the first time from current Cabinet Secretary Sir Gus O'Donnell.
Inquiry chairman Sir John Chilcot said: "As we draft our report it is clear that there are some areas where we need further detail.
"We will, therefore, be seeking further evidence on those matters. I am committed to taking the majority of this evidence in public.
"In some cases we will be writing to witnesses or government departments asking them to provide a written statement of events, responding to specific questions set out by the committee. In other cases we will be taking oral evidence."
Mr Blair mounted a vigorous defence of the 2003 invasion of Iraq when he appeared before the inquiry on January 29, insisting he had no regrets over removing Saddam Hussein and would do the same again.
But critics of the war and families of the 179 UK troops who died in the conflict condemned his appearance, saying he evaded the panel's questions and refused to admit his mistakes.
As Mr Blair left the hearing after giving evidence for six hours, one audience member heckled, "You are a liar," and another added, "and a murderer".
On US television 10 days later, he attacked the hunt for a "conspiracy" and a "scandal" over his decision to commit UK troops to Iraq.
No date has been fixed for Mr Blair's second half-day appearance.