GUANTANAMO BAY NAVAL STATION, Cuba , 14 January — Amnesty International reiterated its call that all those in US custody following the military operations in Afghanistan must be treated humanely, with full respect for international standards, as the first captives, 20 Al-Qaeda and Taleban prisoners, spent their second night in detention at this remote US military outpost in outdoor cells with metal roofs.

"Reports that Al-Qaeda and Taleban prisoners being transferred to a US base in Guantanamo, Cuba, may be drugged, hooded and shackled during the 20-hour transportation flight are worrying," a statement from the rights group stressed prior to the transportation and detention of the prisoners.

Military officials said Saturday that all was going smoothly inside the detention camp in eastern Cuba, where the prisoners were given meals and showers, and allowed to walk around outside their cells with military escorts.

In a letter to the authorities earlier this week, Amnesty International expressed concern at photos showing detainees in Afghanistan hooded while under guard by US Marines. Hooding suspects in detention may violate international standards prohibiting "cruel, inhuman or degrading" treatment.

The standards emphasize that the term "cruel, inhuman or degrading" covers mental as well as physical abuse, including holding detainees in conditions that deprive them, even temporarily, of the use of any of their natural senses such as sight or hearing or awareness of time or place. The hooding or blindfolding of suspects during interrogation also violates international standards.

According to international standards restraints may be used when strictly necessary as a precaution against escape, damage or injury. However, if restraints are necessary, they must be applied humanely, with adequate opportunity for the prisoner to move limbs, use the bathroom and eat and drink. Furthermore, sedating prisoners for other than medical purposes would be in breach of international standards. Also any administration of sedative drugs should be in accordance with purely medical criteria.

"Housing detainees in Guantanamo in 6x8 feet chain-link ‘cages’ at least partially open to the elements would also fall below minimum standards for humane treatment," the organization said. Standards for the treatment of detainees require adequate shelter from the elements. The cage size would be less than that considered acceptable under US standards for ordinary prisoners confined to cells.

"This was sort of our test run. It went extremely well," camp security head Army Col. Terry Carrico said. Reporters at the US naval base weren’t being allowed to visit the camp. The prisoners arrived Friday afternoon and had their hands bound as they were led off a cargo plane at the Caribbean base, surrounded by heavily armed US Marines.

It rained during the night, but the simple metal roofs of the outdoor cells kept the prisoners dry, Carrico said Saturday. During an exercise period Saturday, he said the prisoners were allowed to walk outside their cells, but each was to have a military police guard on each shoulder, and each would have his hands bound, he said.

Carrico said the turquoise surgical masks that some prisoners wore upon arrival had been removed once in the camp. They wore the masks after initial tests suggested the presence of tuberculosis, and those prisoners were to undergo chest X-rays to confirm whether they were infected, he said.

The shackled prisoners began to step off the Air Force C-141 cargo plane about an hour after it touched down Friday afternoon following 13,000-kilometer journey. They were surrounded by heavily armed Marines as they were led to two white school buses.

Several detainees appeared to struggle with the 50-plus Marines who led them to the buses. At least one prisoner was sedated on the trip to the base, and two were forced to their knees on the tarmac before being allowed to stand again and walk to the buses. Journalists watching the arrival were not allowed to bring still or video cameras, with the Pentagon citing Geneva Convention bans "against insults and public curiosity." The military, however, photographed the arrival.

After their arrival in Cuba, the prisoners were taken to a Navy ferry that carried them across Guantanamo Bay to their camp. They were isolated in temporary cells with walls of chain-link fence, where they slept on mats under halogen floodlights. The prisoners were given sheets, and blankets were available, Carrico said. Translators were available, and each Muslim prisoner would be issued a copy of the Qur’an if he didn’t have one, Carrico said.

Amnesty International said the plan to house detainees in "cages" would "fall below minimum standards for humane treatment." But US officials insisted that neither the heavy security nor the detention methods violated prisoners’ rights.

The US Army said the prisoners’ treatment would be "humane but not comfortable." The Red Cross and other groups are to monitor conditions. The US is reserving the right to try Al-Qaeda and Taleban captives on its own terms and is not calling them "prisoners of war," a designation that would invoke the Geneva Convention. Some human rights activists are concerned that US officials plan military tribunals and lowered standards of due process.

Amnesty, meanwhile, is also concerned for the safety of approximately 80 prisoners held by the United Front (commonly known as the Northern Alliance) at Shibarghan, northern Afghanistan, as they may be at risk of torture or extrajudicial execution.

The prisoners, 18 of whom are said to be seriously injured, belonged to Taleban forces who had surrendered to the United Front in Kunduz. Amnesty has also called for an inquiry into the deaths in Qalai-Jhangi prison, focusing specifically on what triggered the fighting; any shortcomings in the holding and processing of the prisoners; as well as the proportionality of the response by the United Front, US and the UK forces. The United Front has stated that it would allow such an inquiry to take place. The UK has rejected such a proposal as has the US-led coalition.