LONDON (AFP) - Former prime minister Tony Blair will give long-awaited testimony to Britains Iraq war inquiry at the end of next week on January 29, officials said Monday. Blair, who controversially backed the US-led 2003 invasion of Iraq alongside president George W. Bush, will face a full day of questioning at the Chilcot inquiry, according to an updated schedule on the probes website. The former premier has long been expected to be the star witness at the inquiry, which was launched in November after the withdrawal of virtually all of Britains forces, six years after the invasion. Last month Blair admitted in a television interview that he would have backed the war even if he knew Iraq did not have weapons of mass destruction (WMD), triggering fresh criticism. Blair, who quit as premier in 2007 and is now the Middle East Quartets envoy, told the BBC it would still have been right to remove Iraqi leader Saddam Hussein because of the threat he posed to the region. Interest in Blairs appearance at the inquiry is intense: a public ballot was held Monday for public seats at the hearings, and the lucky few will be allowed into either the morning or afternoon sessions, but not both. Blair stood shoulder-to-shoulder with Bush over the 2003 invasion, but faced a major backlash in Britain over the decision. He resigned as prime minister two and a half years ago despite having led his Labour Party to three successive election wins, handing the role to his finance minister Gordon Brown. An Internet campaign has been launched for Blair to face tough questions about why he took Britain into the unpopular war, amid criticisms the inquiry panel has been too easy on some witnesses. But inquiry chairman John Chilcot has insisted that the probe was not here to provide public sport or entertainment but to get to the facts. Also due to appear at the inquiry next week is Peter Goldsmith, the former British attorney general who advised Blair on the legality of the war. Two key ministers from the time of the Iraq war are due to appear this week: then defence minister Geoff Hoon on Tuesday, and then foreign secretary Jack Straw on Thursday. Blairs chief of staff at the time, Jonathan Powell, was due to give evidence later Monday. His former chief spin doctor Alastair Campbell appeared before the inquiry last week, and fiercely denied sexing up a dossier which claimed Iraq could launch chemical or biological weapons within 45 minutes. In a defiant appearance, Campbell said that while the controversial document could have been clearer, he still defended every single word of it-and the invasion itself. Current Prime Minister Gordon Brown-who Campbell said was one of the key ministers Blair consulted in the run-up to war-will appear after this years general election, expected in May. Brown, who was Blairs finance minister at the time, insisted last week that he has nothing to hide over the Iraq war.