GUANTANAMO, Cuba - A dozen peace activists, including Cindy Sheehan and the mothers of a Guantanamo prisoner and a New York firefighter killed on 9/11, marched here yesterday to demand the closing of the U.S. detention camp at Guantanamo Bay, five years after the first terror suspects arrived.

The protest in Cuba came as demonstrators in the Philadelphia region, Washington and London, as well as U.N. Secretary-General Ban Ki-moon, also called for the camp's closure.

"What I've read happens in this prison makes me sick to my stomach," Sheehan said outside the post where Cuban officials stopped the protesters from entering the Cuban military territory to reach the main gate of the U.S. base.

Sheehan, who became a war protester after her son Casey, 24, died in Iraq in April 2004, joined the other women in fastening bouquets of yellow and pink wildflowers to the barbed-wire fence, as well as a bright pink cloth reading, "Women say NO to torture."

The protesters had hoped to march down the lonely asphalt road past the Cuban mine fields dotted with scrub brush and cactus, but Cuban Lt. Col. Edilberto Rivera said that all civilians were barred from the zone.

Zohra Zewawi, the mother of British detainee Omar Deghayes, traveled from the United Arab Emirates with another son, Taher Deghayes, to join the protest. She said her son had been tortured and blinded in one eye after he was imprisoned in September 2002 and still has not been charged.

Adele Welty, whose son Timothy, a firefighter, was killed at the World Trade Center, called on Americans to contact Congress to demand that Guantanamo be closed and that the detainees receive fair trials.

The protesters also included Asif Iqbal, 25, a British Muslim who spent 21/2 years at the prison. He expressed support for those still inside. "Every day, every minute, they are in our thoughts," he said.

The U.S. military is holding about 395 men on suspicion of links to al-Qaeda or the Taliban, including about 85 who have been cleared to be released or transferred to other countries. The military says it wants to charge 60 to 80 detainees and bring them to trial.

Critics say the camp, where most of the prisoners face indefinite incarceration, is an affront to democratic values. Allegations of abuse have fueled worldwide outrage.

The military says that the detention center is vital to the fight against terrorism and that instances of abuse have been investigated and the perpetrators disciplined. The camp's commander, Adm. Harry B. Harris, says aggressive interrogation tactics are no longer used.

Army Col. Lora Tucker, a spokeswoman for the center, said the military had no plans to acknowledge the protest yesterday or to increase security at the outside gates.

At the United Nations, the new secretary-general echoed his predecessor, Kofi Annan, in urging the Bush administration to shut down the prison.

In Washington, about 100 protesters were arrested at a federal courthouse after a brief demonstration demanding the prison's shutdown. Earlier, outside the Supreme Court, several hundred demonstrators and dozens of rights activists wearing orange prison jumpsuits and black hoods also called for the closure of Guantanamo. About 100 people protested outside the U.S. Embassy in London.

House Majority Leader Steny H. Hoyer (D., Md.) said yesterday that the Democratic-controlled House planned to scrutinize the administration's handling of the Guantanamo center with an eye toward closing it.