Former US President Jimmy Carter has alleged that the Bush administration tortures prisoners in violation of international law.
President George W Bush recently defended his administration's techniques used to interrogate terror suspects, insisting that "this government does not torture people".
However, Carter disagreed with Bush in an interview with CNN.
"That's not an accurate statement if you use the international norms of torture as has always been honoured - certainly in the last 60 years since the Universal Declaration of Human Rights was promulgated," Carter said on Wednesday.
Responding to the remarks, a senior White House official said: "Our position is clear. We don't torture".
The official added, "It's just sad to hear a former president speak like that."
In the interview, Carter also criticised some of the 2008 Republican presidential candidates, calling former New York Mayor Rudy Giuliani "foolish" for his contention that the US should be open to the use force on Iran.
"I hope that he doesn't become president and try to impose his conviction that we need to go to war with Iran," Carter said.
Democratic Senators Hillary Clinton of New York and Barack Obama of Illinois, both forerunners among the Democratic presidential candidates, also drew Carter's criticism for refusing recently to pledge to withdraw all troops from Iraq by the end of their first terms if they win the presidency in 2008.
"I disagree with their basic premise that we'll still be there. I think the American people want out," Carter said.