Johan Steyn, the third most senior judge in the United Kingdom, told an independent television channel on Tuesday the suspects were being held at the US naval base in Cuba in conditions of "utter lawlessness".
"As a lawyer brought up to admire the ideals of American democracy and justice I would have to say that I regard this as a monstrous failure of justice," Steyn told Channel Four.
His comments come amid frantic efforts by UK to have nine British detainees being held at Camp X-Ray in Guantanamo Bay returned to face trial at home rather than being tried by a US military court.
"The question is whether the quality of justice envisaged for the prisoners at Guantanamo Bay complies with the minimum international standards for the conduct of fair trials. The answer can be given quite shortly. It is a resounding no," the judge said.
"As a lawyer brought up to admire the ideals of American democracy and justice I would have to say that I regard this as a monstrous failure of justice"
Steyn further alleged that Washington's motives for holding the prisoners was "to put them beyond the rule of law, beyond the protection of any courts and at the mercy of victors".
"The procedural rules do not prohibit the use of force to coerce the prisoners to confess," he said. He urged the UK government to speak out on behalf of all the 660 detainees from 42 different countries.
"It may be appropriate to pose a question: Ought our government to make plain publicly and unambiguously our condemnation of the utter lawlessness at Guantanamo Bay?" Steyn asked.
The US defends the detentions, insisting the suspects captured during and after the US-led offensive in Afghanistan in 2001 were enemy combatants ineligible for normal legal process.
US heavy-handedness has, however, been condemned by civil rights groups worldwide.