The Organization for Security and Cooperation in Europe says the campaign against terrorism is being used as an excuse to inflict physical and mental torture on suspects in many countries.
The OSCE focused on the prevention of torture at a two-day meeting, attended by delegates from most of its 55-member countries.
The head of the OSCE Office for Human Rights, Christian Strohal, told delegates there can be no legal excuse for torture.
"There is no question to my mind, and I think to many people's minds, that the fight against terrorism since 9/11 has increased the danger that pretexts [for torture] are being sought," he said. "And, we have to fight against that danger."
Mr. Strohal said confessions resulting from the use of torture should not be used in court cases.
Rachel Denber of Human Rights Watch, based in New York, said there are serious concerns regarding the treatment of detainees in U.S. custody in countries such as Afghanistan.
"There are some instances, in which U.S. forces detain terror suspects, or people suspected of working with the Taleban, or of being Taleban fighters - detaining them - and then handing them right over to Afghan authorities, knowing full well, they have a terrible record on torture," she said.
Ms. Denber says detainees are being held in secret places in Afghanistan, with no public access or international supervision.
Ms. Denber said some countries are more ready to use torture since the September 11 attacks, believing the United States will turn a blind eye, if the torture helps the war on terrorism.
Human rights groups say mental, as well as physical torture is a problem in former communist countries, such as Uzbekistan. They cite old Soviet practices, including forcible confinement of human rights activists to psychiatric hospitals.
The OSCE says Uzbekistan has recently adopted an action plan against torture, but the group wants to see it implemented.