At an event to commemorate the 1948 Universal Declaration of Human Rights (UNDR), the Nobel laureate said the detention of suspected al Qaeda and Taliban members at the U.S. naval base in Guantanamo Bay, Cuba, was a "huge blot on a democracy".

"Whoever imagined that you would hear from the United States and from Britain the same arguments for detention without trial that were used by the apartheid government," Tutu told Reuters.

Tutu is chairman of the Elders, a group of prominent international statesmen that includes former U.S. President Jimmy Carter, anti-apartheid icon Nelson Mandela and his Mozambican-born wife Graca Machel.

The group is spearheading a campaign to get one billion people to sign a pledge reaffirming the principles of the UNDR, passed by the United Nations General Assembly on December 10, 1948.

Tutu, who helped lead the struggle to overthrow white minority rule in South Africa, said he was surprised so many Americans had accepted the argument that the Guantanamo detentions were necessary because of national security.

"It is exactly what the apartheid government used to say here," the Anglican cleric said.

His remarks come amid a growing outcry over alleged abuses at Guantanamo, which in the aftermath of the September 11, 2001, attacks on the United States was used as a mass detention centre for suspected violent Islamic radicals.

Critics have said that the United States has circumvented international law by holding detainees without charge, often for years, and violated their human rights with forced confessions and torture tactics.

President George W. Bush says the detentions are lawful, humane and necessary as part of its fight against extremists in Iraq, Afghanistan and elsewhere in the world.

The U.S. Supreme Court has agreed to hear a legal challenge by Guantanamo inmates who are contesting their detention.