The Cabinet was shown the "full extent" of Lord Goldsmith's advice on the legality of invading Iraq, Britain's top civil servant has said.
Lord Goldsmith denies being 'leaned on'
It had been thought ministers were shown only a summary of the attorney general's opinion.
But Cabinet Secretary Sir Andrew Turnbull said "there is no other version" of the text.
Lib Dem leader Charles Kennedy said this "astonishing revelation" suggested "confusion at the heart of government".
'No longer version'
"The prime minister must now clarify the situation which is undermining public trust," Mr Kennedy said.
"He must provide a clear statement about what took place regarding the legal advice.
"Can it really be true that the legal basis on which we went to war consisted of a parliamentary answer and not a full legal opinion?"
Sir Andrew said the attorney general gave the Cabinet a presentation and a copy of his parliamentary answer about his advice.
Giving evidence on Thursday to the House of Commons' Public Administration Select Committee he said: "There is not a longer version of that advice.
"There is no other version. This is the definitive statement of his views."
Sir Andrew said the presentation given to the Cabinet "did not purport to be a summary" of Lord Goldsmith's advice.
"It was the definitive advice that he had reached," he said.
He indicated there was not enough time for Lord Goldsmith to prepare a fuller statement because it was required quickly - when it became clear there would be no second UN resolution.
It was only a summary in that it summarised Lord Goldsmith's views, he said. It was not a summary of a larger document.
But Sir Andrew then caused confusion by saying there were "other papers" which the government would not disclose.
His comments appear to be in direct conflict with the Butler report on intelligence failings.
The report said the prime minister's office had asked Lord Goldsmith to put his view on the legal situation in writing, which he did in a formal minute to Mr Blair 10 days before the Cabinet meeting.
Lord Goldsmith has repeatedly denied being "leaned on" by Number 10 to change his view on the legality of war without a second UN resolution.