US President Barack Obama says he has ordered a review of the way US spy agencies gather intelligence. It follows a string of embarrassing revelations which include bugging millions of phone calls.France, Germany and Spain are some of the countries now seeking explanations.
Obama's comments came during an interview with Fusion, a cable network joint venture between ABC and Univision on Monday.
He called for a review of the agency's operations, "to make sure that what they're able to do doesn't necessarily mean what they should be doing".
Obama said he is the "final user" of all intelligence gathered by the National Security Agency and other intelligence agencies in the US and that the White House gives the NSA "policy direction", but that "their capacities continue to develop and expand".
His statements echoed, head of US Senate's Intelligence Committee, Dianne Feinstein, a Democrat, who earlier on Monday called for a "total review of all intelligence programmes" after reports that American spies eavesdropped on German chancellor Angela Merkel.
Feinstein said Obama was not informed either that Angela Merkel's communications were being collected since 2002.
"With respect to NSA collection of intelligence on leaders of US allies, including France, Spain, Mexico and Germany, let me state unequivocally: I am totally opposed," Feinstein said in a statement.
"Unless the United States is engaged in hostilities against a country or there is an emergency need for this type of surveillance, I do not believe the United States should be collecting phone calls or emails of friendly presidents and prime ministers," Feinstein said.
"The president should be required to approve any collection of this sort."
Her statement follows reports based on new leaks from former NSA systems analyst Edward Snowden indicating that the NSA listened to Merkel and 34 other leaders.
The Spanish El Mundo newspaper on Monday reported the US had monitored 60 million phone calls in that country during one month. The report comes days after similar stories of NSA spying in France and Germany.
In response, German authorities on Monday cited last week's non-binding resolution by the European Parliament to suspend a post-9/11 agreement allowing the US access to bank transfer data to track suspicious transactions.
Sabine Leutheusser-Schnarrenberger, German justice minister, said on Monday she believed the US were using the information to gather economic intelligence.
"It really isn't enough to be outraged," she told a radio station. "This would be a signal that something can happen and make clear to the Americans that the (EU's) policy is changing."
Asked if the NSA spying had been used to boost economic interests, White House spokesman Jay Carney said: "We do not use our intelligence capabilities for that purpose. We use it for security purposes."
He added that the US may need "additional constraints" on its spying activities.