Archbishop Desmond Tutu has joined in the growing chorus of condemnation of America's Guantanamo Bay prison camp.
Archbishop Tutu says the camp is a "horrendous subversion" of the law
He said the detention camp was a stain on the character of the United States as a superpower and a democracy.
He also attacked Britain's 28-day detention period for terror suspects, calling it excessive and untenable.
His comments follow a UN report calling for the closure of the camp where some 500 "enemy combatants" have been held without trial for up to four years.
Speaking on the BBC's Today programme, Archbishop Tutu said he was alarmed that arguments used by the South African apartheid regime are now being used to justify anti-terror measures.
"It is disgraceful and one cannot find strong enough words to condemn what Britain and the United States and some of their allies have accepted," he said.
The respected clergyman said the rule of law had been "subverted horrendously" and he described the muted public outcry - particularly in America - as "saddening".
Only a handful of the approximately 500 detainees have been tried
Archbishop Tutu also attacked Tony Blair's failed attempt to hold terrorist suspects in Britain for up to 90 days without charge.
"Ninety days for a South African is an awful deja-vu because we had in South Africa in the bad old days a 90-day detention law," he said.
Under apartheid, as at Guantanamo, people were held for "unconscionably long periods" and then released, he said.
"Are you able to restore to those people the time when their freedom was denied them? If you have evidence for goodness sake produce it in a court of law," he said.
"People with power have an incredible capacity for wanting to be able to retain that power and don't like scrutiny."
Archbishop Tutu's comments add to the mounting international pressure on US President Bush to close the detention centre at Guantanamo Bay.
The UN Secretary General, Kofi Annan, said on Thursday that America must close the camp "as soon as is possible".
Jan 2002: First "illegal combatants" arrive at Camp X-ray. Transferred to Camp Delta in April
Feb 2002: More than 100 out of nearly 600 detainees stage first of many hunger strikes
Oct 2002: First releases include four men returned to Afghanistan and Pakistan
Feb 2004: US officials announce the first charges against two detainees
Mar-May 2004: Dozens of detainees released
July 2004: First military tribunal
Jan 2005: US announces investigation into allegations of abuse
May 2005: US magazine report - later retracted - alleges copies of the Koran mishandled by guards, sparking worldwide protests. US later confirms five cases of mishandling
His comments backed a UN report recommending that the US try the approximately 500 inmates, or free them "without further delay".
A senior British minister has also called for the camp to be closed.
Speaking on the BBC television Question Time programme on Thursday, Peter Hain said he would prefer to see Guantanamo Bay close.
He also indicated that the UK Prime Minister, Tony Blair, agreed with him.
The US has dismissed most of the findings of the UN report which include allegations of torture.
White House spokesman Scott McClellan on Thursday rejected the call to close the camp, saying the military treated all detainees humanely.
"These are dangerous terrorists that we're talking about," he said.