The Council of Europe, the European Union's chief rights watchdog, said its own investigations into secret prisons in Poland and Romania had been vindicated by the US president's revelations.
Rene van der Linden, the Council of Europe Parliamentary Assembly president, said on Thursday: "Our work has helped to flush out the dirty nature of this secret war, which, we learn at last, has been carried out completely beyond any legal framework."
Bush said on Wednesday that the US held dozens of suspects at undisclosed overseas locations and 14 of those held had now been sent to the US military prison at Guantanamo Bay.
Wolfgang Kreissl-Doerfler, a German lawmaker and member of a European Parliament committee investigating the allegations said: "The location of these prison camps must be made public.
A Romanian airbase is said to
house one of the prisons
"We need to know if there has been any complicity in illegal acts by governments of EU countries or states seeking EU membership."
He urged EU member Poland and candidate country Romania to speak out about accusations that they hosted secret jails.
Polish officials said on Thursday the government may launch an inquiry into the existence of secret CIA prisons on its soil.
Poland's conservative government, which took power last September, has repeatedly rejected the Council of Europe's accusations, saying it had been assured by its leftist predecessors that such prisons never existed.
British EU parliamentarian Sarah Ludford said: "Bush exposes not only his own previous lies. He also exposes to ridicule those arrogant government leaders in Europe who dismissed as unfounded our fears about extraordinary rendition."
Bush said on Wednesday that a small number of detainees, including the planner of the September 11 attacks, Khalid Sheikh Mohammed, had been kept in CIA custody in order to be "questioned by experts and, when appropriate, prosecuted for terrorist acts".
International lawmakers and civil rights campaigners have long called on Bush to acknowledge that the US used a network of secret prisons and have transferred prisoners between them on covert flights.
Manfred Nowak, the UN special investigator on torture, called Bush's acknowledgment of CIA secret prisons "progress", but said their existence was already known.
Bush is pressing Congress to quickly pass administration-drafted legislation authorising the use of military commissions for trials of terrorist suspects after the Supreme Court in June ruled that trying detainees in military tribunals violated US and international law.
He said that the interrogation techniques used were tough, but did not constitute torture.
Alexander Downer, Australia's foreign minister, has said that the CIA's secret imprisonment and interrogation of terror suspects had achieved a great deal for the "war on terror".
Downer said Australia had benefited directly from the programme, citing the arrests of Mohammed, who was al-Qaeda's link to the Southeast Asian group Jemaah Islamiyah, and that group's operations chief, Indonesian Riduan Isamudin.
Downer conceded that the prison programme was controversial but said critics should accept that extraordinary measures were needed to deal with the global threat of terrorism revealed by the September 11 attacks.