The notorious US detention camp in Guantanamo Bay has been hit by fresh allegations of human rights abuses, with claims that dozens of children were sent there - some as young as 14 years old.
Lawyers in London estimate that more than 60 detainees held at the terrorists' prison camp were boys under 18 when they were captured.
They include at least 10 detainees still held at the US base in Cuba who were 14 or 15 when they were seized - including child soldiers who were held in solitary confinement, repeatedly interrogated and allegedly tortured.
The disclosures threaten to plunge the Bush administration into a fresh row with Britain, its closest ally in the war on terror, only days after the Attorney General, Lord Goldsmith, repeated his demands for the closure of the detention facility. It was, he said, a "symbol of injustice".
Whitehall sources said the new allegations, from the London-based legal rights group Reprieve, directly contradicted the Bush administration's assurances to the UK that no juveniles had been held there. "We would take a very, very dim view if it transpires that there were actually minors there," said an official.
One child prisoner, Mohamed el Gharani, is accused of involvement in a 1998 al-Qa'ida plot in London led by the alleged al-Qa'ida leader in Europe, Abu Qatada. But he was 12 years old at the time and living with his parents in Saudi Arabia.
After being arrested in Karachi in October 2001, aged 14, he has spent several years in solitary confinement as an alleged al-Qa'ida-trained fighter.
One Canadian-born boy, Omar Khadr, was 15 when arrested in 2002 and has also been kept in solitary confinement. The son of a known al-Qa'ida commander, he is accused of killing a US soldier with a grenade in July 2002 and was placed top of the Bush administration's list of detainees facing prosecution.
"It would surely be really quite stupid to allow the world to think you have teenagers in orange jumpsuits and shackles, spending 23 hours a day locked up in a cage," a source added. "If it's true that young people have been held there, their cases should be dealt with as a priority."
British officials last night told the IoS that the UK had been assured that any juveniles would be held in a special facility for child detainees at Guantanamo called Camp Iguana. But the US admits only three inmates were ever treated as children - three young Afghans, one aged 13, who were released in 2004 after a furore over their detention.
The row will again focus attention on the Bush administration's repeated claims that normal rules of war and human rights conventions do not apply to "enemy combatants" who were al-Qa'ida or Taliban fighters and supporters. The US insists these fighters did not have the same legal status as soldiers in uniform.
Clive Stafford Smith, a legal director of Reprieve and lawyer for a number of detainees, said it broke every widely accepted legal convention on human rights to put children in the same prison as adults - including US law.
"There is nothing wrong with trying minors for crimes, if they have committed crimes. The problem is when you either hold minors without trial in shocking conditions, or try them before a military commission that, in the words of a prosecutor who refused to take part, is rigged," he said. "Even if these kids were involved in fighting - and Omar is the only one who the military pretends was - then there is a UN convention against the use of child soldiers. There is a general recognition in the civilised world that children should be treated differently from adults."
Because the detainees have been held in Cuba for four years, all the teenagers are now thought to have reached their 18th birthdays in Guantanamo Bay and some have since been released.
The latest figures emerged after the Department of Defense (DoD) in Washington was forced to release the first ever list of Guantanamo detainees earlier this month. Although lawyers say it is riddled with errors - getting numerous names and dates of birth wrong - they were able to confirm that 17 detainees on the list were under 18 when taken to the camp, and another seven were probably juveniles.
In addition, said Mr Stafford Smith, they had credible evidence from other detainees, lawyers and the International Red Cross that another 37 inmates were under 18 when they were seized. One detainee, an al-Jazeera journalist called Sami el Hajj, has identified 36 juveniles in Guantanamo.
A senior Pentagon spokesman, Lt Commander Jeffrey Gordon, insisted that no one now being held at Guantanamo was a juvenile and said the DoD also rejected arguments that normal criminal law was relevant to the Guantanamo detainees.
"There is no international standard concerning the age of an individual who engages in combat operations... Age is not a determining factor in detention. [of those] engaged in armed conflict against our forces or in support to those fighting against us."