The man appeared behind Lord Justice Leveson at the High Court to denounce Mr Blair as a 'war criminal' and accuse him of profiting from a deal with investment bank JP Morgan as a consequence of the 2003 invasion.
The former premier appeared unruffled by the interruption and immediately denied the claims made by the heckler.
Lord Justice Leveson apologised to Mr Blair and ordered an investigation into the security breach.
Mr Blair - who was greeted by around 25 anti-war protesters as he arrived for his day of evidence - conceded to the inquiry his Labour administrations were too close to media organisations but said such links between politicians and the press were 'inevitable'.
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PICTURES: Tony Blair at the Leveson Inquiry
