During his own emotionally charged interview on Sunday morning, Mr Campbell was asked by Andrew Marr about Tony Blair's assertion that he believed the case for Saddam Hussein having weapons of mass destruction was proved "beyond doubt" by the intelligence.
Mr Marr asked: "If beyond doubt is not established in the intelligence when this inquiry looks at the intelligence, does it then follow, yes or no, the prime minister misled Parliament?"
Mr Campbell, who has a new novel out, replied that Mr Blair "did not mislead Parliament" before being pressed again. He began to reply but paused, looking close to tears.
He said: "I've been through a lot on this Andrew. And I've been through a lot of that inquiry... and... Tony Blair, I think, is a totally honourable man."
Mr Campbell said the media was obsessed with "settling your scores and setting your own agenda".
"You did it again this morning, which is probably why I'm a bit upset, this constant sort of vilification.
"You compared the novel to the dossier, and it's all fiction and all the rest of it. It's not. And I just think the way that this whole issue has developed now where I don't think people are interested in the truth anymore, Andrew."
He added: "I'm sorry if I do get upset about this but I was there alongside Tony, I know how that decision weighed on him, I know the care that we took."
Mr Campbell said he understood why people were "upset" about the decision to become involved in the conflict.
But, he added: "The reason people are going over it again and again and again is because those who do disagree with the judgment that Tony Blair made actually don't want to see the other side of the story."
'Many people upset' by Iraq
Shadow foreign secretary William Hague, speaking later on the Andrew Marr Show, said he was sorry that "Mr Campbell was upset" by the questions but "we are all upset by what happened in Iraq".
Mr Hague added: "I am very upset that it seems our soldiers were often sent into action without the necessary equipment because of poor political decision making, that there was no plan for the aftermath of the invasion of Iraq.
"We are all upset. I am upset about the fact that in a debate in which I supported Tony Blair at the time of the Iraq war, we were told that the intelligence was authoritative and extensive and beyond doubt, and it seems listening to the Chilcot inquiry, that that was not the case.
"I think many people are upset in different ways about it, and that must not stop us learning the lessons.
Asked if he thought Tony Blair had misled Parliament, Mr Hague said: "I feel that increasingly in many aspects of the case Parliament was misled but I think to come to an overall judgement on that question we have to see the inquiry result as a whole - this inquiry has been set up after years of pressure from us and other opposition parties."
William Hague: Increasingly feels that in many aspects MPs were misled
Later in his interview with Andrew Marr Alastair Campbell was asked about the reports of Mr Brown's tears during the Piers Morgan interview set to be broadcast next weekend.
He said he advised Mr Brown ahead of the programme, which he hoped would help the PM reach a wider audience.
"The only communication that works now really is where people are being utterly authentic. The public, they hear all this stuff about spin, they know the media spin, the politicians do it and they can see when people are being authentic."
He added: "If Gordon just talks about some of these issues as he really feels then maybe the public will see a different side."
But Mr Campbell said he did not believe the prime minister, whose daughter died in 2002 10 days after being born prematurely, had gone on television "with the purpose of crying".
The PM's wife, Sarah Brown, posted a message on Twitter on Sunday to a member of the studio audience who had sent her a message hoping she was ok.
Mrs Brown said: "Thank you for coming to watch the interview too - it was a great audience, so warm."
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