BRUSSELS -- Amid a growing outcry over American snooping on foreigners that threatens to cloud European-U.S. trade talks and President Barack Obama's visit to Berlin, the European Union's top justice official has demanded in unusually sharp terms that the United States reveal what its intelligence is doing with personal information of Europeans gathered under the Prism surveillance program revealed last week.
Viviane Reding, the Union's combative commissioner of justice, told Attorney General Eric Holder in a letter sent on Monday evening that individual citizens of European countries had the right to know whether their personal information had been part of intelligence gathering "on a large scale."
In the letter, seen Tuesday by the International Herald Tribune, she also asked what avenues were available to Europeans to find out whether they had been spied on, and whether they would be treated similarly to U.S. citizens in such cases.
"Given the gravity of the situation and the serious concerns expressed in public opinion on this side of the Atlantic, you will understand that I will expect swift and concrete answers," Mrs. Reding wrote.
Speaking for a continent where snooping carries ghastly echoes of fascist or communist regimes, Mrs. Reding challenged Mr. Holder to answer a list of detailed questions by Friday, when they are expected to speak face-to-face in Dublin at a ministerial meeting scheduled before the Prism spy operation came to light.
In Berlin, where Mr. Obama will speak next week before the Brandenburg Gate, privacy is a highly sensitive political issue and the Prism revelations have stirred a furor.
"You can be sure that this will be one of the things the chancellor addresses when President Obama is in Germany," said Steffen Seibert, spokesman for Angela Merkel, who grew up in the former Communist East.
Germany's interior minister, Hans-Peter Friedrich, said his ministry wants to establish whether any Germans' right to privacy had been infringed and is preparing a "catalog of questions" for its American counterparts.
The justice minister, Sabine Leutheusser-Schnarrenberger, in a guest editorial for the Web site Spiegel Online, called the revelations about the U.S. surveillance "deeply disconcerting" and possibly "dangerous."
"In a democratic constitutional state, security is not an end in itself, but serves to secure freedom," Ms. Leutheusser-Schnarrenberger wrote.
Mrs. Reding -- who has irked U.S. authorities in the past by threatening companies like Google for overstepping E.U. privacy standards -- suggested Mr. Holder's responses could shape the outcome of important trans-Atlantic initiatives like trade talks.
Europe has been a frequent critic of the United States in recent years for jeopardizing individual liberties by filtering vast volumes of information on European bank transfers and in airline passenger records to fight terror plots.
Mrs. Reding's letter is another sign that the growth of government surveillance that began under the Bush administration after Sept. 11, 2001, and has expanded under the Obama administration, continues to touch raw nerves far beyond the United States.
Under the Prism program, the United States is said to have collected Internet data on foreigners abroad from companies including Google, Facebook, Microsoft, Apple, Yahoo and Skype.
The revelations have prompted members of the European Parliament, a directly elected body of representatives from across the Union that meets in Brussels and Strasbourg, to demand that data protection be included in upcoming U.S.-European talks on a long sought trade pact.
Any "trade pact will have to fully ensure the highest standards of data privacy for all citizens," and an ongoing reform of Europe's data protection law "must guarantee these standards for E.U. citizens when using U.S.-based Internet companies," Hannes Swoboda, an Austrian member of the parliament who is president of the Socialists & Democrats group, said in a statement on Tuesday.
"It is no good the E.U. having strict regulation on data protection if those standards are not guaranteed when using U.S.-based Internet companies," he said.
Talks on a trade deal were endorsed by Mr. Obama in February and involve efforts to drop trade barriers between the E.U. and the United States and to synchronize regulations.
The talks are expected to be conducted by Mrs. Reding's colleague, Karel De Gucht, the E.U. trade commissioner -- but the Parliament would have a final say over any such deal under its right, in force since 2009, to veto treaties with third countries.
In the strongest demonstration against U.S. policy, the Parliament in 2010 blocked an agreement allowing U.S. authorities access to European banking data from a cooperative responsible for routing trillions of dollars daily among banks, brokerage houses, stock exchanges and other institutions.
The cooperative, the Society for Worldwide Interbank Financial Telecommunication, or Swift, is based near Brussels. It provided the U.S. authorities with personal data after the attacks of Sept. 11, 2001.
The Parliament eventually gave its approval to a revised agreement in July 2010. But some lawmakers have threatened to renew demands to scrap that agreement, and others, with the United States.
In a thinly veiled warning to Mr. Holder about the trade pact, Ms. Reding said relations between the United States and Europe could be undermined by concerns about privacy, which many in Europe regard as an inviolable right.
In her letter, Mrs. Reding said she "is accountable before the European Parliament, which is likely to assess the overall trans-Atlantic relationship also in the light of your responses."
In nine detailed questions, Ms. Reding asked Mr. Holder how much data-sifting the United States is conducting, whether those activities target individuals, and whether the surveillance involves issues beyond national security.
Mrs. Reding also pushed Mr. Holder to tell her "what avenues" are available to citizens of countries in the European Union to obtain information about whether their personal information has been examined under the Prism program and other programs, and whether Europeans have similar access to that information as Americans.
E.U. officials said Tuesday that the outcry over Prism will reinforce anxiety about how personal data is used.
On Tuesday, the president of Italy's privacy authority, Antonello Soro, warned against the growing pressure from police and national authorities all over the world to obtain citizens' private information. "The generalized and indiscriminate surveillance of citizens, reasonably also European citizens, beyond any criminal evidence, through data coming from phone calls or from the Web, is a very, very serious thing" he wrote to the Italian Parliament.
For Mrs. Reding, the chance to push back against Washington is a welcome opportunity.
Two years ago, she was forced to soften her initial proposals for data privacy rules in order to accommodate U.S. intelligence gathering. That followed intense pressure on the European Commission, the E.U.'s governing body, from the Obama administration.
Under Mrs. Reding's original proposal, companies in Europe that store or process personal data would need authorization from a "supervisory authority" before they could transfer personal information outside the Union at the request of a foreign government or court.
That article is no longer in the latest draft of Europe's data privacy laws but, even before the furor erupted over Prism, some members of the European Parliament were asking for similar safeguards to be reintroduced.
Chris Cottrell contributed reporting from Berlin and Gaia Pianigiani from Rome.
This article originally appeared in The New York Times.