The Attorney General "misled" the Government over the case for going to war with Iraq, Clare Short has told the inquiry into the conflict.
Ms Short, MP for Birmingham Ladywood, who was international development secretary at the time, said she was not aware of Lord Goldsmith's "doubts and his changes of opinion" over the issue.
Lord Goldsmith gave legal advice before Britain committed to going to battle against Saddam Hussein in March 2003.
Giving evidence to the inquiry panel, Ms Short said: "I think he misled the Cabinet. He certainly misled me, but people let it through."
In light of Lord Goldsmith's "doubts and his changes of opinion" that have since emerged, Ms Short added: "I think for the Attorney General to come and say there's unequivocal legal authority to go war was misleading."
Ms Short claimed that Lord Goldsmith was "leaned on" by former Prime Minister Tony Blair to agree that the war was legal.
The Attorney General provisionally advised Mr Blair in January 2003 that it would be unlawful to invade Iraq without a further United Nations Security Council resolution.
But he changed his mind a month later after being persuaded to talk to senior US government lawyers and Britain's ambassador to the UN, Sir Jeremy Greenstock.
Ms Short told the inquiry: "Lord Goldsmith said he was excluded from lots of meetings - that's a form of pressure. It was suggested to him that he go to the US to get advice about the legal position.
"You have got the Bush administration who have very low respect for international law. It seems the most extraordinary place in the world to go to get advice about international law."
She dismissed as "nonsense" Sir Jeremy's advice to Lord Goldsmith that other permanent UN Security Council members accepted another resolution was not essential.
Ms Short added: "I think all that was leaning on - sending him to America, excluding him and then including him."
Mr Blair and Lord Goldsmith both denied in their evidence to the inquiry that the Attorney General was put under pressure.
Ms Short described the Cabinet meeting on March 17, at which Lord Goldsmith presented his final and unequivocal advice that the war would be legal without a further resolution.
She recalled that the Attorney General was sitting in the seat of Robin Cook, who resigned as Leader of the House of Commons over the war that day.
The former international development secretary said it was not true - as claimed by Mr Blair and Lord Goldsmith in their testimony to the inquiry - that the Cabinet was given the chance to ask questions.
She said she started to ask the Attorney General why the advice was so late but was "jeered at" to be quiet by other Ministers.
When she later repeated the question to Lord Goldsmith, he replied: "Oh, it takes me a long time to make my mind up."
Ms Short told the inquiry that she was "stunned" by the legal advice but accepted it at the time. She said: "I thought, in the teeth of war, the Attorney General of the UK coming to Cabinet to give legal advice - this is a very serious, monumental thing and that's his advice, and I'm very surprised but you must accept it."
But she said the Cabinet would have had second thoughts if it had seen the detailed 13-page legal advice that Lord Goldsmith sent Mr Blair on March 7.
"I think people would have thought it was much more equivocal and risky and wanted to be more sure," she said.
Ministers should also have been told that the Foreign Office's two most senior legal advisers believed there was no legal authority for the war, she added.
The Cabinet was not told that Lord Goldsmith secretly asked Mr Blair on March 14, 2003 to give a written confirmation that Saddam Hussein was in breach of previous UN resolutions, the inquiry heard.
Ms Short said: "I think we should have been told that. That was all kept from us and we were just given the PQ (Parliamentary Question) answer that said unequivocal legal authority, no questions asked, no doubt.
"I think that's misleading."
The inquiry also heard that Ms Short warned Mr Blair weeks before the war began that the US was unprepared for running the country after the invasion.
She said the US body set up to rebuild post-invasion Iraq, the Office for Reconstruction and Humanitarian Assistance, was "under-staffed, under-resourced and under-prepared for the scale of the challenge".
Appealing for more time, Ms Short wrote to the prime minister on March 5 2003: "You should be aware that the US and the international humanitarian community are not properly prepared to deal with the immediate humanitarian concerns."
She also cautioned Mr Blair that reconstructing Iraq without an explicit UN mandate would breach international law.
Ms Short resigned as international development secretary nearly eight weeks after the invasion on March 20 2003.
Ms Short told the panel it became clear she was being frozen out of discussions over Iraq from the summer of 2002.
"It was clear that there was some kind of block on communication - normal communications were being closed down," she said. "Everything that has happened since makes me know there was deliberate blockage."
Ms Short also criticised the decision-making process and claimed it was hindered by "secretiveness and deception".
"There was never a meeting which said 'What's the problem, what are we trying to achieve, what are our military/diplomatic options?'. We never had that coherent discussion," she said.
She added: "In the case of Iraq, there was secretiveness and deception."
She told the panel that planning for post-conflict Iraq avoided a "humanitarian catastrophe" but she claimed the invasion still had terrible consequences.
"What we did in Iraq was very dangerous, ill-considered and has made Iraq more dangerous and has destroyed lots of property and destroyed lots of people's lives," she said.
Despite her reservations over the conflict, Ms Short said it did not affect her department's planning for the war. She said she was focused on making sure Britain "did it right" after the conflict.
Ms Short said she asked for extra money to prepare for aftermath Iraq but received no reply from the Treasury.
Letters declassified ahead of today's hearing show Ms Short wrote to Mr Blair on March 5, 2003 warning that it would be "impossible" to take a "leading role in humanitarian delivery" without more cash.
She said Gordon Brown, the then Chancellor, was being "marginalised" in the weeks before the invasion.
"Brown was pushed out and marginalised at the time and having cups of coffee with me and saying 'Tony Blair is obsessed with his legacy and he thinks he can have a quick war and then a reshuffle etc'," she said.
She said Mr Brown, in discussions with her, spoke of his concerns over what would happen "beyond Iraq".
"He was worried about what is beyond Iraq," she said. "He would say 'On Iraq, we must uphold the UN'. I would say 'I agree'."
Ms Short was damning about Mr Blair's failure to ask Washington to delay the invasion despite warnings that the military and aid officials were not ready.
She said: "I think he was so frantic to be with America that all that was thrown away. If he had done that, his place in history and the UK's role in the world would have been so much more honourable.
"Britain needs to think about this, the special relationship. What do we mean by it?
"Do we mean we have an independent relationship and we say what we think, or do we mean we just abjectly go wherever America goes and that puts us in the big league? That's a tragedy."
Ms Short also criticised US planners for ignoring predictions that there could be chaos and sectarian fighting after the invasion.
She said: "They believed their own propaganda and the British Government's capacity to think better than that was just subverted and thrown away, to our deep eternal shame."
Ms Short said Mr Blair persuaded her against resigning on the same day as Mr Cook by assuring her that the UN would have the lead role in reconstructing Iraq and that US president George Bush would support the creation of an independent Palestinian state.
Asked why she didn't resign earlier, she said: "If I knew then what I know now, I would have."
Ms Short was clapped by the audience in the inquiry chamber after she finished giving her testimony.
The only other witness who has received applause for their evidence is Elizabeth Wilmshurst, a former senior Foreign Office legal adviser who was the only British civil servant to quit over the war.