The prisons in northeastern Poland and southeast Romania were part of a "global spider's web" of detentions and illegal transfers spun out around the world by the United States and its allies after the September 11, 2001 attacks, said the report by Council of Europe investigator Dick Marty.

Marty also suggested that Nato and the United States reached a secret deal in 2001 allowing the Central Intelligence Agency to run the covert prisons.

"We believe that the framework for such assistance was developed around Nato authorisations agreed on 4 October 2001, some of which are public and some which remain secret," Marty said in the report.

He said former Polish president Aleksander Kwasniewski and Romania's former leader Ion Iliescu as well as current President Traian Basescu authorised the programme and should be held accountable.

"We have sufficient grounds to declare that the highest state authorities were aware of the CIA's illegal activities on their territories," the report said.

He also named the national security advisers, military and intelligence chiefs in both countries as having had a hand in the interrogation programme set up as part of Washington's "war on terror."

Under an agreement reached with the United States, at least eight terror suspects were held in Poland including Abu Zubaydah, a close associate of Osama bin Laden and Khalid Sheikh Mohamed, considered al-Qaeda's mastermind of the September 11 attacks.

"The CIA brokered 'operating agreements' with the governments of Poland and Romania to hold its high-value detainees in secret detention facilities on their respective territories," said the report.