Polish Prime Minister Kazimierz Marcinkiewicz said on Saturday he would order an investigation into allegations that the CIA detained suspected terrorists at secret prisons in Poland.
Officials in Marcinkiewicz's government and its predecessor have denied the allegations by Human Rights Watch and in U.S. media but Marcinkiewicz said an investigation was needed since the reports could threaten Poland's security.
"I will order an investigation at all possible locations, to determine whether there is any evidence at all that such events took place on our territory," Marcinkiewicz said on the private television channel TVN 24.
"This matter must finally be closed, because it could prove dangerous for Poland," added Marcinkiewicz, whose cabinet was sworn in on Oct. 31.
On Friday, the newspaper Gazeta Wyborcza quoted Marc Garlasco, an analyst with watchdog group Human Rights Watch, as saying that, until recently, Poland was the main location for CIA interrogations in Europe.
Poland is one of Washington's leading allies in Europe, where it angered European Union heavyweights Germany and France by sending troops to join the U.S.-led war in Iraq.
The United States has declined to comment on the reports, which have caused controversy on both sides of the Atlantic.
Human Rights Watch was not immediately available for comment on Saturday.
Garlasco was quoted on Friday as saying the CIA had set up two detention centers in Poland, which were closed shortly after the Washington Post published an article about secret prisons last month.
The Polish centers held a quarter of the 100 detainees estimated to be held in such camps worldwide, he said.
Separately, on Saturday Gazeta Wyborcza quoted staff at an airport in Szymany, northeast Poland, as saying planes belonging to the CIA had landed there at least five times since 2002.
"It was always the same — the planes parked on the tarmac far from the buildings. They never fuelled, and there was never any military guard presence ... no passengers were ever registered at the airport," Wyborcza quotes one employee as saying.
It quoted employees as saying buses with darkened windows, which they believed came from a nearby intelligence school, drove up to the planes but from the airport buildings it was impossible to see if anyone boarded or left the aircraft.