Lord Falconer has made his strongest attack yet on Guantanamo Bay by denouncing it as a "shocking affront to the principles of democracy".
Speaking in Sydney, the Lord Chancellor accused the US of "deliberately seeking to put detainees beyond the rule of law in Guantanamo Bay".
But he also stressed the UK remained "a close and staunch ally" of America.
The peer told the BBC he believed it was time to air his private disapproval of the detention camp in public.
He added that he was making the speech "with the authority of the government".
"In June of this year, I said Guantanamo Bay was a recruiting ground for terrorism and I found it intolerable," he told BBC Radio 4's Today programme.
Guantanamo Bay has angered human rights groups
"The USA is a close and staunch ally of the UK. I have in time raised the issue in private.
"As time goes on, private words have to get replaced, to some extent by public views and that's why it has happened in that way."
Liberal Democrat leader Sir Menzies Campbell questioned why the Lord Chancellor had "increased the volume of his rhetoric".
"Why has he done this in Australia and not in the UK? Does he speak with the authority of the prime minister?" he said.
"And when may we expect the prime minister to condemn Guantanamo in similar terms?"
Some 450 terror suspects are thought to be detained at the controversial camp in Cuba.
In his speech on Wednesday, Lord Falconer said: "It is a part of the acceptance of the rule of law that the courts will be able to exercise jurisdiction over the executive.
"Otherwise the conduct of the executive is not defined and restrained by law.
"It is because of that principle, that the USA, deliberately seeking to put the detainees beyond the reach of the law in Guantanamo Bay, is so shocking an affront to the principles of democracy.
"Without independent judicial control, we cannot give effect to the essential values of our society."
But an extra sentence was added by Lord Falconer to the crucial section of the speech criticising the detention camp.
The extra comment was: "That we disagree on this issue does not detract from the fact that the USA is a close and staunch ally of the UK." This part of the address was not included in the version of the speech sent to journalists on Thursday night.
Lord Falconer made the comments in the Magna Carta Lecture, delivered annually in Australia by senior British legal figures, to an audience of senators, MPs, judges and academics at the Supreme Court of New South Wales.
The Attorney General, Lord Goldsmith, has described the Guantanamo camp as "unacceptable" and called for it to be closed.
Prime Minister Tony Blair has been more muted, simply calling it an "anomaly".