U.S. officials defended the intelligence community's surveillance programs in the wake of allegations that it monitored European allies, as the latest reports threatened relations between the U.S. and a host of world powers.
European officials, angered over the new revelations, said the program could threaten ongoing negotiations on a trans-Atlantic trade treaty.
"Partners do not spy on each other," said EU Justice Commissioner Viviane Reding. "We cannot negotiate over a big trans-Atlantic market if there is the slightest doubt that our partners are carrying out spying activities on the offices of our negotiators. The American authorities should eliminate any such doubt swiftly."
According to Reuters, a spokesman for the German government also said German Chancellor Angela Merkel would speak to President Obama about the surveillance reports in the near future, and implied that a larger European response would follow.
The statements came as U.S. officials said that they would discuss the new allegations -- reported in Sunday's editions of the German newsweekly Der Spiegel -- directly with European Union officials.
President Obama, speaking at a press conference in Tanzania, said his staff was "still evaluating the article" and officials would "communicate to our allies appropriately."
But he stressed that the U.S. works closely with its European allies. "If I want to know what Chancellor Merkel is thinking, I will call Chancellor Merkel," he said. "Ultimately, we work so closely together that there's almost no information that's not shared between our various countries.
Without going into detail, a statement from the Office of the Director of National Intelligence argued that the programs are similar to what other countries do.
"As a matter of policy, we have made clear that the United States gathers foreign intelligence of the type gathered by all nations," the statement said.
According to Der Spiegel, the NSA planted bugs in the EU's diplomatic offices in Washington and infiltrated the building's computer network.
Similar measures were taken at the EU's mission to the United Nations in New York, the magazine said. It also reported that the NSA used secure facilities at NATO headquarters in Brussels to dial into telephone maintenance systems that would have allowed it to intercept senior officials' calls and Internet traffic at a key EU office nearby.
The report in Der Spiegel cited classified U.S. documents taken by NSA leaker and former contractor Edward Snowden that the magazine said it had partly seen. It did not publish the alleged NSA documents it cited, nor say how it obtained access to them.
The Guardian also published an article Sunday alleging NSA surveillance of the EU offices, citing classified documents provided by Snowden. The Guardian said one document lists 38 NSA "targets," including embassies and missions of U.S. allies like France, Italy, Greece, Japan, Mexico, South Korea, India and Turkey.
The Guardian article cited a 2007 document that told of a device with the code name "Dropmire" that was "implanted on the Cryptofax at the EU embassy, DC." According to NSA documents cited in the article, the Cryptofax is used to send cables to foreign affairs ministries in European capitals.
The reports were the latest bombshell in a nearly monthlong global debate over the reach of U.S. surveillance that aims to prevent terror attacks. The two programs, both run by the National Security Agency, pick up millions of telephone and Internet records that are routed through American networks each day. Reports about the programs have raised sharp concerns about whether they violate public privacy rights at home and abroad.
Several European officials -- including in Germany, Italy, France, Luxembourg and the EU government itself -- said the new revelations could scuttle ongoing negotiations on the trade treaty, which seeks to create jobs and boost commerce by billions annually in what would be the world's largest free trade area.
European Parliament President Martin Schulz, said he was "deeply worried and shocked about the allegations of U.S. authorities spying on EU offices." And Luxembourg Foreign Minister and Deputy Prime Minister Jean Asselborn said he had no reason to doubt the Der Spiegel report, and rejected the notion that security concerns trump the broad U.S. surveillance authorities.
In Washington, the statement from the national intelligence director's office said U.S. officials planned to respond to the concerns with their EU counterparts and through diplomatic channels with specific nations. It did not provide further details.
The Associated Press contributed to this report.