The attorney general last night warned that the continuing operation of the Guantanamo Bay detention camp was "unacceptable".
Lord Goldsmith's comments are the strongest statement yet from the British government about the US camp in Cuba, where many of the suspected terrorist inmates have been held for years without trial or charge.
He told a meeting at the Royal United Services Institute last night that the "greatest challenge" facing democratic states at the moment was how to balance the rights of individuals against the rights of the community to be protected against terrorism.
The British government had clashed with its own judiciary over this subject a number of times, he noted, citing a recent court defeat over control orders and the law lords' ruling that holding terrorist suspects at Belmarsh prison without trial was illegal.
However, Lord Goldsmith insisted that the right to a fair trial was a "principle on which there can be no compromise", which was why the UK was unable to accept that the tribunals offered to Guantanamo inmates "offered sufficient guarantees" of fairness.
This position led the government to negotiate for the return of all British detainees in the camp, but despite that, the attorney general said the existence of the camp still "remains unacceptable".
"It is time, in my view, that it should close. Not only would it, in my personal opinion, be right to close Guantanamo as a matter of principle, I believe it would also help to remove what has become a symbol to many - right or wrong- of injustice," he said.
"The historic tradition of the United States as a beacon of freedom, liberty and of justice deserves the removal of this symbol."
However, a spokesman for the US state department said that while government would "like nothing better" than to close the camp, the inmates still posed too much of a threat.
"The fact of the matter is that the people there are dangerous people," said Sean McCormack.
"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."
Previously Tony Blair has only said the camp is an "anomaly" that "must be ended" - something the Foreign Office has insisted is akin to calling for its closure, but which has lacked the impact of a clear public condemnation.