Europe's papers are examining the legal and moral issues of what the CIA calls "rendition" - clandestine transfers of terror suspects.
Germany is one of the countries reported as a landing spot
Many front-page editorials and commentaries highlight US Secretary of State Condoleezza Rice's refusal to expose alleged US secret prisons and flights.
German newspapers call for clarification of how much the previous German government knew.
The current issue of Der Spiegel reports that the German government has a list of more than 400 overflights and landings by alleged CIA planes. This prompted an opposition party to demand that it seek a "comprehensive explanation" from Washington.
The weekly magazine says the list - drawn up by air traffic control - shows at least 437 flights passed over or through Germany.
France's Le Monde believes Ms Rice's visit to Europe "will be difficult, because Europe's leaders are expecting clarification on the CIA's secret prison affair".
The paper says hundreds of "rendition" flights went through Germany, "a situation which is embarrassing that country's government and its new chancellor, Angela Merkel".
It notes that Ms Rice has "remained firm" and "refused to respond concretely" to the allegations.
German papers are dominated by allegations that former Interior Minister Otto Schily and the Schroeder government were informed of the transportation of terror suspect Khalid al-Masri.
Last weekend the Washington Post said the CIA kidnapped the German citizen in Macedonia and took him to Afghanistan, where, according to his defence lawyer, he was at least threatened with torture.
It said the German authorities were asked to help with covering up the case.
"It looks like Germany is taking part in the American way of fighting terrorism, called rendition, without wishing to get its hands dirty as the Americans are doing," says Sueddeutsche Zeitung.
"The law must set politicians' limits," it says, warning that legal action over "the abduction of a German citizen" may have been "prevented or at least hampered".
The paper accuses the government of "hypocrisy" over the reported torture of terror suspects.
A commentary in Tageszeitung argues that "clarification" of the Masri affair is "urgently needed" if Germany's relationship with the United States is to be "normalised" on a "non-criminal basis".
For Germany's Frankfurter Rundschau, "there is a deep, lasting gulf between the moral-political approach of the neo-conservatives in the US, represented by the Bush administration, and the basic political consensus in Germany".
Frankfurter Allgemeine Zeitung notes that Chancellor Merkel is "already being closely watched" to see whether her policy towards the United States is going to be "too close, too cordial".
Adevarul in Romania - the next stop on Ms Rice's tour - believes a visit "initially aimed at strengthening transatlantic co-operation and signing agreements on setting up American military bases" will now be dominated by "the controversy over the CIA planes and secret prisons".
Taking a broader view, Russia's business broadsheet Kommersant believes the row about CIA operations in Europe has revealed the limitations of the US-European "rapprochement".
"Morally the Europeans are not ready to accept the sacrifices in the struggle against international terrorism which George Bush is demanding from them. Hence, today's calls from Condoleezza Rice to unite in the face of a common enemy sound like a voice crying in the wilderness."
BBC Monitoring selects and translates news from radio, television, press, news agencies and the Internet from 150 countries in more than 70 languages. It is based in Caversham, UK, and has several bureaus abroad.