Rice admitted that the United States was "different now" in regards to interrogation law.
She said: "Now, there has been a long evolution in American policy about detainees and about interrogations.
"We now have in place a law that was not there in 2002 and 2003," she said, referring to the passage in 2005 of the Detainee Treatment Act that prohibits cruel, inhuman and degrading treatment.
"We now know a great deal more about how al-Qaeda operates thanks to what we were able to learn from those early detainees"
Condoleezza Rice, US secretary of state
The secretary of state would not specify which techniques were approved to interrogate detainees suspected of links to al-Qaeda up to a year after the 2001 attacks.
A report from the US justice department earlier in the week said sleep disruption, prolonged shackling of hands and feet or wrapping a detainee's head in duct tape were some of the methods used at the Guantanamo Bay, Cuba, detention facility, where Washington keeps many of its terrorism suspects.
Last month, George Bush, the US president, also admitted that waterboarding - a technique which inducing reflexive choking and feelings of suffocation by pouring water over a subject's cloth-covered face - was approved at the highest levels of government and used, at least in one instance, on Khaled Sheikh Mohammed - the suspected mastermind of the 2001 attacks.
Rice said: "We now know a great deal more about how al-Qaeda operates thanks to what we were able to learn from those early detainees.