The United States has bugged European Union offices and gained access to EU internal computer networks, according to secret documents cited in a German magazine, the latest in a series of exposures of alleged US spy programmes.
Der Spiegel quoted from a September 2010 "top secret" US National Security Agency (NSA) document that it said whistleblower Edward Snowden had taken with him, and the magazine's journalists had seen in part.
The document outlines how the NSA bugged offices and spied on EU internal computer networks in Washington and at the United Nations, not only listening to conversations and phone calls, but also gaining access to documents and emails.
The document explicitly called the EU a "target".
If these reports are true, it's disgusting.
The NSA also targeted telecommunications at the Justus Lipsius building in Brussels, home to the European Council, the collective of EU national governments, according to the magazine.
Snowden, a former NSA contractor, earlier this month revealed the existence of the so-called PRISM programme operated by the the US security agency.
US officials could not immediately be reached for comment.
In reactions published on the magazine's website, European Parliament chief Martin Schulz said more information was needed, but if the spying allegations proved correct, "it's a huge scandal".
"On behalf of the European Parliament, I demand full clarification and require further information speedily from the US authorities with regard to these allegations," he said in an emailed statement.
Luxembourg Foreign Minister Jean Asselborn told Der Spiegel: "If these reports are true, it's disgusting."
"The United States would be better off monitoring its secret services rather than its allies. We must get a guarantee from the very highest level now that this stops immediately."
Snowden's disclosures in foreign media about US surveillance programmes have ignited a political furore in the United States and abroad over the balance between privacy rights and national security.
Snowden fled to Hong Kong in May, a few weeks before the leaks. He has been holed up in a Moscow airport transit area since last weekend.
The leftist government of Ecuador, which is reviewing his request for asylum, said on Saturday that the US has asked them to refuse the request.