The US has rejected the UK government's calls for closing down the Guantanamo Bay prison camp for terror suspects.
The US holds some 500 terror suspects at Guantanamo Bay
US officials said the camp housed dangerous people who could pose a fresh threat if they were released.
The UK Attorney General Lord Goldsmith said on Wednesday the camp's existence was "unacceptable" and tarnished the US traditions of liberty and justice.
The criticism shows a significant shift in the UK's stance on the camp run by its US ally, our correspondent says.
UK Prime Minister Tony Blair has, in the past, called the prison camp at the US base in Guantanamo Bay, Cuba, an "anomaly".
But in the strongest criticism yet from a UK government minister, Lord Goldsmith said the camp had become a symbol of injustice.
"The historic tradition of the United States as a beacon of freedom, liberty and of justice deserves the removal of this symbol," he said.
Lord Goldsmith is said to have serious doubts over whether the indefinite detention of "enemy combatants" is legal or fair.
Responding to the criticism, State Department spokesman Sean McCormack said the US "would like nothing better" than to close Guantanamo down at some point in the future.
Echoing the words of US President George W Bush - who in a TV interview on Sunday said he would like to "end" the detention centre - he said: "Nobody wants to be a jailer for the world."
"But the fact of the matter is that the people there are dangerous people," Mr McCormack said.
"One thing we don't want to do is release people now who might at some point in the future end up on the battlefield facing our troops or somebody else's troops, or committing acts of terrorism against civilians."
A Pentagon spokesman said: "The dangerous detainees at Guantanamo include terrorist trainers, bomb makers and would-be suicide bombers, many who have vowed to return to the fight."
Around 490 detainees are in Guantanamo Bay, which opened in January 2002.
There has been international criticism of conditions at the US camp and the length of time detainees have been held there without trial.
Rights groups have said the detainees, held on suspicion of involvement in terrorism, are mistreated through cruel interrogation methods - a charge the US denies.
Lord Goldsmith told the London-based Royal United Services Institute there was a case for limiting some rights for collective security.
But he said the right to a fair trial should never be compromised.
Nine British nationals at Guantanamo were returned to the UK in 2004 and 2005 after government intervention.
Lord Goldsmith said the UK was "unable to accept that the US military tribunals proposed for those detained at Guantanamo Bay offered sufficient guarantees of a fair trial in accordance with international standards".
He went on to defend the European Convention on Human Rights and the UK's Human Rights Act.
"Fundamental rights must be protected if we are to preserve our democracies but given the current threat to our national security we have to be flexible about how we achieve this," he said.
Lord Goldsmith also defended the creation in the UK of new criminal offences in the Terrorism Act 2006 to counter "some features of al-Qaeda type terrorism which distinguish it from other forms of crime".
"Where we depart from traditional ways of guaranteeing civil liberties we should be clear that our actions are proportionate to the threat and needed to meet it," he said.