His was the first official reaction in Iran to a US Senate report that torture of suspects in the years following the 9/11 attacks on the United States was far more brutal than acknowledged and failed to produce useful intelligence.
"Today, US govt. is symbol of tyranny against humanity; even American ppl are faced w cruelty," Khamenei wrote on Twitter, referring to a speech he had made in 2007.
Tehran is regularly criticised from abroad over its own human rights record, especially regarding the high number of people it executes, and over restrictions on press and religious freedoms.
But it invariably retorts that these accusations are politically motivated, in turn criticising Western nations for trying to impose on the Islamic republic their concept of human rights.
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"They claim human rights & trample its basics in their prisons, in interactions w nations & even w their own ppl," Khamenei added from a 2010 speech.
"They claim they've a prideful nation; US govts. debased & misguided their ppl who aren't aware of many realities," he added.
The report, released Tuesday, said the Central Intelligence Agency also misled the White House and Congress with inaccurate claims about the programme's usefulness.
Khamenei's tweets drew extensive comments.
Some recalled the numerous cases of people who have died in detention in Iran in recent years, and the case of a woman hanged in October for stabbing to death a man she said had tried to sexually assault her.