The report by Swiss Sen. Dick Marty also accused Germany and Italy of obstructing probes into alleged secret detentions by the CIA.

Top terror suspects Khalid Sheikh Mohammed and Abu Zubaydah were held and interrogated in Poland, according to the report, which cited unidentified CIA sources. Mohammed is the self-proclaimed mastermind of the Sept. 11, 2001, attacks and Abu Zubaydah is a suspected senior al-Qaida operative.

The report also said the "highest state authorities" in countries involved knew of the alleged detention centers.

Jerzy Szmajdzinski, Poland's defense minister from 2001-05, sarcastically brushed aside the accusations, saying: "Of course, I organized everything and gave them a red-carpet welcome." He declined further comment on "political fiction."

Romanian Sen. Norica Nicolai rejected Marty's findings as "totally unfounded."

CIA spokesman Paul Gimigliano said: "While I've yet to see the report, Europe has been the source of grossly inaccurate allegations about the CIA and counterterrorism."

President Bush did not acknowledge the CIA's secret detention program until September 2006, when he announced that the agency had just moved Mohammed and 13 other suspected terrorists to Guantanamo Bay. He did not say where the prisons were located.

In Germany, government spokesman Thomas Steg denied it hindered the probe.

"The government knows of media reports about apparent prisoner transports and secret prisons, but the government itself has no information on such transports and facilities," Steg said.

"To date, Mr. Marty has in his other reports also failed to provide any evidence that what is alleged is actually true."

The report said collaboration by U.S. allies was critical to the secret detention program, which took place in the framework of NATO's security policy.

"The secret detention facilities in Europe were run directly and exclusively by the CIA," it said.

"While it is likely that very few people in the countries concerned, including in the governments themselves, knew of the existence of the centers, we have sufficient grounds to declare that the highest state authorities were aware of the CIA's illegal activities on their territories," it said.

Poland and Romania hosted the prisons under a special post-Sept. 11 CIA program to "kill, capture and detain" high-value terrorist suspects, wrote Marty, a Swiss senator investigating the alleged role of Council of Europe states in the CIA program.

Evidence of secret flights — at least 10 flights to Poland between 2002 and 2005 — show the pivotal role played by Poland and Romania as drop-off points, the report says.

"There is now enough evidence to state that secret detention facilities run by the CIA did exist in Europe from 2003 to 2005, in particular in Poland and Romania," the report said.

Marty did not identify his sources, saying they were people "who had worked or still worked for the relevant authorities, in particular intelligence agencies."

"We have never based our conclusions on single statements and we have only used information that is confirmed by other, totally independent sources," the report said, adding that where possible, information was cross-checked in the relevant countries, in the U.S., or in documents and data.

In Italy, the first trial involving the CIA's extraordinary rendition program opened on Friday, without the presence of any of the 26 American defendants accused of kidnapping an Egyptian terrorist suspect. The case has irritated the historically robust U.S.-Italian relationship, and coincided with Bush's arrival in Rome.

Last year, Marty accused 14 European nations of colluding with U.S. intelligence in a web of rights abuses to help the CIA spirit terror suspects to illegal detention facilities. He said evidence suggested that CIA-linked planes carrying terror suspects had landed at airports in Timisoara, Romania, and Szymany, Poland, and likely dropped off detainees there.

His second report confirmed Szymany as a drop-off point in Poland, where at least 10 flights — six from Afghanistan — landed.

"High-value detainees" were held in Poland at the Stare Kiejkuty intelligence training base, the report said, citing multiple sources. Americans had full control of the detainees, it said.

He added that neither Polish nor U.S. sources would discuss operational details of the detentions at Stare Kiejkuty.

The report said Washington lured Romania into cooperating with "formidable" support for its accession to NATO — the "biggest prize."

Marty said he recognized the "seriousness of the terrorist threat" but added: "The fight against terrorism must not serve as an excuse for systematic recourse to illegal acts, massive violation of fundamental human rights and contempt for the rule of law."