The much-anticipated findings of the Chilcot inquiry will be boycotted by several of the families of British soldiers killed in the conflict who say it will be a “whitewash”.
The relatives of 179 Britons killed in Iraq have expressed dismay at the way the investigation has been handled.
The mother of Gary Nicholson, 42, who died when he was shot down in an aircraft in 2005, said: "I'm absolutely disgusted. I'm not going because it will be a whitewash.
"Tony Blair has got blood on his hands. He will have covered his back and [George] Bush's back.”
Many have called on Mr Blair, the Prime Minister at the time, to be held accountable for war crimes.
But lawyers at the International Criminal Court have ruled out prosecuting Mr Blair, claiming the decision to go to war is not in the court's remit.
Mr Blair has repeatedly refused to comment on the inquiry before it is published. Speaking on Sky News' Murnaghan on Sunday, he said:
“I have said many times over these past years I will wait for the report then I will make my views known and I will express myself fully and properly.
"I'm not getting into the politics or the detail of it before we actually get it".
A project tracking the number of documented civilian deaths in Iraq, Iraq Body Count, puts the figure of those killed since the beginning of the war at between 160,000 and 180,000. Other estimates are higher.
The inquiry, conducted by Sir John Chilcot, has been plagued by delays. It has taken six years to write and stands at two million words.
Janice Proctor, mother to one of the youngest British soldiers killed in the war, said she wouldn’t go to read the report on Wednesday:
"It's been horrendous, I'm very apprehensive about this.
“This man [Blair] has put 179 kids to the slaughter - there's no justice.
"It [the report] is not going to give me any closure or comfort.
“I'm not going down on the day, I'm not going to waste two hours of my life reading it," she said.
