Short, a long-time critic of Blair who served as International Development Secretary in his government, disputed evidence the former prime minister gave last week to an inquiry into the war.
Short voted in favor of the 2003 invasion but quit Blair's government shortly afterwards because she said Blair had conned her into thinking the U.N. would play a lead role in post-war Iraq.
Last Friday, Blair made a robust defense of his decision to go to war, telling the inquiry that Saddam Hussein had posed a threat to the world and had to be disarmed or removed. He said there had been substantive discussion with senior ministers in the cabinet.
But Short told the Chilcot inquiry, which is examining Britain's role in the war and its aftermath, that she had been excluded from talks and that Blair had not wanted Iraq discussed in the cabinet because he was afraid of leaks to the media.
There was secretiveness and deception on top of that, she said. Normal communications were being closed down.
She accused Blair of being frantic to support the United States and said claims the French would have vetoed any second U.N. resolution authorizing military action had been untrue.
In my view that was a lie, a deliberate lie, she said.
She said current prime minister Gordon Brown, who was finance minister at the time, had been marginalized.
Brown himself will give evidence later this month or at the start of March and commentators have said the inquiry could damage the ruling Labour party, which is trailing in opinion polls, before an election due by June.
Short accused former Attorney General Peter Goldsmith of not telling the cabinet of his doubts about the legality of war, nor that senior Foreign Office lawyers believed it would be illegal without a second U.N. resolution.
Goldsmith has said he initially doubted the war's legality and only concluded it would be lawful without such a resolution a week before the invasion, days before the cabinet was briefed.
I think he misled the cabinet, he certainly misled me, but people let it through, Short said.
She told the inquiry she believed Goldsmith had been pressured by Blair, something both men deny, but had no direct evidence to back this up.
Short said there was no imminent threat from Saddam, and said planning for the aftermath of the invasion was inadequate.
There was no reason why it had to be as quick as it was, she said. It was all done on a wing and a prayer.
We could have gone more slowly and carefully and not had a totally destabilized and angry Iraq into which came al Qaeda ... and that would have been safer for the world.
Short quit the Labour Party parliamentary group in 2006 to become an independent MP.
(Editing by Noah Barkin)