Moore, director of "Fahrenheit 9/11," the documentary critical of US President George Bush and the Iraq war, said on Friday that he now wants to take a closer look at the British leader's role in backing the war in Iraq and sending troops into harm's way.
"I personally hold Blair more responsible for this war in Iraq than I do George Bush, and the reason is Blair knows better. Blair is not an idiot. What is he doing hanging around
this guy?" Moore told Reuters in an interview.
"Fahrenheit 9/11," which will hit US cinemas on 25 June, examines links between the Bush family and influential Saudi Arabians, including the family of Usama bin Laden.
The film also contends that Bush used a fear and misinformation to thrust the United States into a war it did not need to fight.
It won the top prize at the Cannes film festival last month.
Britain and Blair have been the staunchest supporters of US-led forces in Iraq, but Moore said that in making "Fahrenheit 9/11" he could focus on only one.
He trained his investigative camera on Bush and that, he said, was a hard decision to make.
"You come at me with anything,
we come back with the truth."
"I struggled with it because, I think, what I decided is that I need to make a separate film about Blair, at some point here. I need to do something about Blair and Britain."
He likened Blair to an older sibling of Bush's and said that, as a parent, when two children get in trouble, the parent usually questions the older one as to how he or she could let such a problem occur.
Meanwhile, Moore said he has steeled himself for efforts by Bush supporters to discredit his film, which he said is already happening with attacks on his website and in newspapers amid the current campaign for the White House.
He has made no secret of the fact that he does not support Bush, and wants his re-election attempt to fail.
Moore's 'war room'
To counteract efforts challenging "Fahrenheit 9/11," he has hired Chris Lehane and Mark Fabiani, two former political advisers to Bill Clinton and Al Gore, to establish a "war room"
that will immediately support any claims made in the movie that come under attack.
The group, he said, will be staffed by six to seven people and will operate 24 hours a day, monitoring newscasts and scanning newspapers, magazines and other publications for
statements made discrediting the movie.
"You come at me with anything, we come back with the truth," Moore said.
Moore, who said he is registered as an independent voter, has yet to throw his support behind presumed Democratic presidential candidate John Kerry.
He said the movie is not an effort to support Kerry's White House bid, and said that if Kerry were elected, "I'd keep my eye on him, too."