SAN JUAN, Puerto Rico — The Red Cross met at Guantanamo Bay with 14 new “high-value detainees,” including Khalid Sheikh Mohammed, the alleged mastermind of the September 11, 2001, attacks, a Pentagon spokesman said.

The encounters apparently mark the first time the 14 detainees have met with anyone other than their captors since they were arrested, held in CIA custody at secret locations, and transferred weeks ago to Guantanamo Bay Naval Base in Cuba. Among them are the alleged architects of the 2000 bombing of the USS Cole and the American Embassy bombings in Kenya and Tanzania.

A spokesman in Washington for the International Committee of the Red Cross, Simon Schorno, declined to discuss specifics or even confirm the encounters had taken place. In meetings with prisoners, Red Cross officials explain that they are visiting as monitors.

“The detainee is not forced to speak to us,” Mr. Schorno said. “It is up to the detainee to raise any issues that fall within our concern, for example past detentions and current conditions. It’s up to the detainee to address whatever he wants to address.”

The Red Cross also can take messages the detainees write, subject to military censorship, for delivery to their families, he said.

But even as the Red Cross wrapped up a more than two-week visit to Guantanamo Bay, the detention center came under increasing criticism.

British Foreign Secretary Margaret Beckett, releasing Britain’s annual report on human rights around the world, said holding hundreds of terror suspects at the camp for years was “unacceptable in terms of human rights” and “ineffective in terms of counterterrorism.”

“It’s widely argued now that the existence of the camp is as much a radicalizing and discrediting influence as it is a safeguard for security,” she said.

Beckett was the highest-ranking British official to criticize the United States so directly for holding suspects for years without trial at Guantanamo.Prime Minister Blair has gone no further in public than calling the camp an “anomaly” which sooner or later must end.

In response to Ms. Beckett’s comments, Sean McCormack, a State Department spokesman, said: “Look, we don’t want Guantanamo open forever. We don’t want to be the world’s jailers. We certainly would look forward to the day when Guantanamo is closed.

“At the moment, it’s housing some very dangerous people, including those who were responsible for the attack on this country which killed 3,000 people.”

The Red Cross, which arrived at Guantanamo Bay on September 25, met the 14 newest detainees this week, Navy Lieutenant Commander Jeffrey Gordon said at the Pentagon.

Mohammed was believed to be the no. 3 Qaeda leader before he was captured in Pakistan in 2003. Also among the 14 new detainees are Ramzi Binalshibh, who is accused of helping plan the Sept. 11 attacks and being a lead operative for a foiled plot to crash aircraft into London’s Heathrow Airport, and Abu Zubaydah, who was believed to be a link between Osama bin Laden and many Al Qaeda cells before he was captured in Pakistan in 2002.

President Bush on September 6 announced they had been moved from CIA custody to Guantanamo for trial.

The detainees reportedly underwent coercive interrogations while being held by the CIA.