Instead, America's top military officer Myers described Guantanamo on Sunday as "essentially a model facility".
In its annual report released on Wednesday, the international rights group called the Guantanamo prison camp, where hundreds of foreign terror suspects are held indefinitely, the "gulag of our times", referring to the notorious prison camps of the Soviet Union.
Asked for his response to the gulag charge, Myers on Sunday replied: "I think it's absolutely irresponsible."
He said the US military had tried to treat its Guantanamo detainees as humanely as possible.
Myers said that 1300 copies of the holy Quran had been handed out to camp inmates in 13 different languages, and that the prison had strived to make "the proper Muslim-approved food" available to detainees.
"I think I'd ask them to go look up the definition of gulag as commonly understood," the US general said of Amnesty's report.
The Guantanamo camp has been the centre of a political and media storm in recent weeks after Newsweek magazine published a report saying interrogators had flushed the Quran in a toilet to rattle Muslim prisoners.