The European Commission will seek answers from Washington on reports the CIA ran secret detention centres in Europe, the bloc's Justice Commissioner Franco Frattini said today.
The Washington Postnewspaper reported this month the CIA had been interrogating suspected al-Qaeda captives at a secret facility in eastern Europe that was part of a covert global prison system with sites in eight countries.
Washington has refused to confirm or deny the report.
Mr Frattini said Jonathan Faull, head of the commission's department for justice, freedom and security, was in Washington on other business but would seek details on the issue.
"I asked him to raise also this point and to ask the US authorities to inform me directly on whether and how these rumours are true or not," Mr Frattini said in London. He said the consequences for member states would be severe if the reports were confirmed.
The Council of Europe, the continent's top human rights watchdog, with no institutional relationship to the EU, has opened an investigation into the allegations.
EU states agreed on Monday to write a joint letter to the United States seeking clarification about the allegations.
US-based organisation Human Rights Watch has identified Romania and EU member Poland as countries that may have been used by the CIA in the alleged secret operation, but both countries have denied it.
Polish Prime Minister Kazimierz Marcinkiewicz said in London today allegations that Polish airports had been used by CIA flights would be investigated.
Romania has said it will allow investigations at two military bases to show they were not used by the CIA.
Spain has said a judge is investigating allegations that the CIA used a Spanish airport as a base for transporting terrorism suspects.