Poland's prime minister says reports of American spy planes secretly flying over and stopping inside Polish territory are "worth checking."
But Prime Minister Kazimierz Marcinkiewicz told reporters in London Thursday he has no information that what he called "any unnecessary episodes" have taken place in Poland.
The European Union's human rights monitor is investigating reports that the U.S. Central Intelligence Agency runs a secret prison network in some European countries and elsewhere. There have also been allegations that CIA aircraft have transported prisoners through EU airspace.
In Hungary, a government spokesman said airplanes belonging to a company used by the CIA have twice landed in that country in the last two years. The official, Boglar Laszlo, said that in both cases, security agents checked the planes, which carried no passengers or cargo.
U.S. officials have neither confirmed nor denied reports of a secret CIA prison system.
Some information for this report provided by AFP and AP.