|Blair's move to join the war in Iraq was one of the most controversial decisions of his premiership. [EPA]
Tony Blair, the former British prime minister, is appearing before an inquiry into the Iraq war to face further interrogation over his decision to join the US-led invasion in 2003.
Blair is appearing before a five-member inquiry panel in London on Friday to clarify his earlier evidence detailing the reasons for joining the war.
There have been widespread doubts over the war's legality.
During his first appearance before the panel in January last year, the former PM, who sent 45,000 troops as part of the invasion, said he had no regrets about the military action in Iraq. He said Saddam Hussein, Iraq's erstwhile ruler, had been a threat to the world who had to be removed or disarmed.
Blair acknowledged that intelligence about Iraq's stockpile of weapons was false. But he said he led the country into war because he couldn't take the risk of Iraq reconstituting its weapons programme.
The US and UK had gone to war, saying Iraq possessed "weapons of mass destruction" - an accusation that later proved to be unfounded.
Blair's steadfast defence of his decision to join the war has angered some of the relatives of the 179 British soldiers killed in Iraq.
'Misled the public'
The decision to go to war was one of the most controversial episodes of the ex-prime minister's 10-year premiership, which ended in 2007. It led to massive protests and accusations he had deliberately misled the public over the reasons for the invasion.
Blair denied such claims and rejected suggestions that he had promised George Bush, the then-US president, military support in 2002, months before attempts to secure United Nations backing for the invasion had foundered.
The Iraq Inquiry is not a trial, but has the stated aim of learning lessons from the UK's involvement in Iraq.
Set up by Blair's successor Gordon Brown, it began in November 2009 and is headed by former civil servant John Chilcot.
"As we begin to write our report, there are a few remaining areas where we need to clarify exactly what happened," Chilcot said on Tuesday.
The ex-prime minister's six-hour appearance in January last year has been the highlight of the probe which has heard from a host of senior military and political figures from Britain and abroad.
Blair is one of a small number of witnesses to have been recalled.