The International Red Cross has called on the United States to grant access to all al-Qaida suspects it is holding, including those reported to be in secret prisons in undisclosed locations.
A spokeswoman says the agency is concerned about the fate of those held.
Wednesday, the Washington Post newspaper and NBC television reported that the CIA has been holding and interrogating top al-Qaida suspects at secret locations outside the United States.
The reports say more than 100 prisoners have been questioned at facilities in at least two eastern European countries, Thailand and other locations. Thailand has denied having secret detention centers, as have officials in many eastern European states.
Earlier Thursday, a European Union spokesman said the European Commission will investigate the reports of the possible use of secret detention facilities in eastern Europe.
U.S authorities have refused to confirm or deny the reports.
Some information for this story provided by AP and Reuters.