Updated

The Pentagon (search ) is preparing to release a dozen or more detainees from its high-security prison camp at the Guantanamo Bay Naval Base (search) in Cuba, possibly including some teenagers.

Some 660 prisoners from 42 countries are held at the Naval base at Guantanamo Bay, many captured during the war against Al Qaeda in Afghanistan. Officials have declined to identify them or their countries or even say exactly how many are held.

An official said Monday that he believed juveniles were among those to be released. News that several boys between the ages of 13 and 16 were among the prisoners drew criticism earlier from human rights groups and a call for their immediate release.

One official said 20 to 30 prisoners would be released from the prison that was opened in January 2002. Another said the number was 12 to 15.

A military official initially told The Associated Press on Monday that 22 prisoners were transferred from the Cuban facility Monday. Later, a more senior Pentagon official said the report was mistaken, and no transfers had taken place.

Defense Department officials denied that the release was the result of a complaint by Secretary of State Colin Powell, who has pressed the Pentagon to move faster in determining the fate of the prisoners at Guantanamo, some of whom have been held a year and a half without charges or access to lawyers. The officials spoke on condition of anonymity.

In what officials have said was a strongly worded letter, Powell told Defense Secretary Donald H. Rumsfeld that eight allies had complained about the holding of their citizens. He said the way the situation was being handled was undermining efforts to win international cooperation in the war on terror.

The release has been in the planning process for several weeks, Pentagon officials said.

An official said juveniles had been among those planned for release weeks ago, but that it was logistically difficult to fly them out of Cuba then because troops were busy with the war to topple and disarm Saddam Hussein in Iraq.

Officials said long ago that some prisoners could be released to their countries if it was certain those countries would deal with them properly. Talks have been under way with various countries, but no results have been announced.

Countries that have said publicly they want their citizens home include Russia, Saudi Arabia, Sweden and Pakistan. Officials said they didn't know the home countries of the prisoners to be released.

Since the prison was opened, only 23 people are known to have been released. They were all men, including one who was mentally ill and another reported to be in his 70s.

Asked Sunday about the prisoners, Rumsfeld said they must be questioned by several government agencies before they can be released, including the FBI, the Justice Department, the State Department, the Pentagon, the CIA and immigration officials. Some agencies are interested in prosecuting the detainees, while others are interested in gathering intelligence information.

The defense secretary said that he, too, would like to see the process move more quickly.

Rumsfeld has said over the past year that the first priority was to interrogate the prisoners for any information they had on terrorist activities or networks. He said they could be released after it was determined there would be no charges against them, they posed no threat and they had no more useful intelligence to offer.

Pentagon officials said Friday that they had finished writing rules for trying terrorist suspects in military tribunals.

Two months after the Sept. 11, 2001, terrorist attacks in Washington and New York, President Bush authorized the establishment of tribunals -- also called military commissions -- to try foreign suspects in the counter-terror war. The effort to write the rules under which the commissions would operate has taken a year and a half.

Speaking on condition of anonymity, the officials said they have some suspects in mind who might be candidates for military trials. They offered no number of trials planned, nor date they might start and said no final decisions have been made.

The Associated Press contributed to this report.