Tony Blair has been recalled to give extra evidence to the Chilcot Inquiry into the Iraq war.
The former UK Prime Minister will answer further questions about the UK's involvement in the conflict at a public session early next year, the inquiry team said in a statement.
Former foreign secretary Jack Straw will also appear as a witness again and former attorney general Lord Goldsmith has been asked to provide further written evidence.
The inquiry will hold a further round of public hearings in London between 18 January and 4 February.
Inquiry chairman 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 gave testimony to the inquiry on 29 January.
He insisted he had no regrets over removing Saddam Hussein and would do the same again.
But anti-war campaigners and families of British troops who died in the conflict condemned his appearance, saying he evaded the panel's questions and refused to admit he made mistakes.
Asked whether he had any regrets at the end of six hours of evidence, Mr Blair said: 'Responsibility but not a regret for removing Saddam Hussein.'
This provoked an angry response from the audience in the inquiry chamber, with one person shouting out: 'What, no regrets? Come on.'
As Mr Blair left, another audience member heckled 'You are a liar', and another added 'And a murderer'.
