BRUSSELS — European leaders united in anger Thursday as they attended a summit overshadowed by reports of widespread US spying on its allies — allegations German Chancellor Angela Merkel said had shattered trust in the Obama administration and undermined the crucial trans-Atlantic relationship.
The latest revelations that the National Security Agency swept up more than 70 million phone records in France and might have tapped Merkel’s own cellphone brought denunciations from the French and German governments.
Merkel’s unusually stern remarks as she arrived at the European Union gathering indicated she was not placated by a phone conversation she had Wednesday with President Obama, or his personal assurances that the US is not listening in on her calls now.
‘‘We need trust among allies and partners,’’ Merkel told reporters in Brussels. ‘‘Such trust now has to be built anew. This is what we have to think about.’’
‘‘The United States of America and Europe face common challenges. We are allies,’’ the German leader said. ‘‘But such an alliance can only be built on trust. That’s why I repeat again: spying among friends, that cannot be.’’
The White House may soon face other irked heads of state and government. The British newspaper The Guardian said Thursday it obtained a confidential memo suggesting the NSA was able to monitor 35 world leaders’ communications in 2006. The memo said the NSA encouraged senior officials at the White House, Pentagon, and other agencies to share their contacts so the spy agency could add foreign leaders’ phone numbers to its surveillance systems, the report said.
The Guardian did not identify who reportedly was eavesdropped on, but said the memo termed the payoff very meager: ‘‘Little reportable intelligence’’ was obtained, it said.
Other European leaders arriving for the 28-nation meeting echoed Merkel’s displeasure. Swedish Prime Minister Fredrik Reinfeldt called it ‘‘completely unacceptable’’ for a country to eavesdrop on an allied leader.
If reports that Merkel’s cellphone had been tapped are true, ‘‘it is exceptionally serious,’’ Dutch Prime Minister Mark Rutte told national broadcaster NOS.
‘‘We want the truth,’’ Italian Premier Enrico Letta told reporters. ‘‘It is not in the least bit conceivable that activity of this type could be acceptable.’’
Echoing Merkel, Austria’s foreign minister, Micheal Spindelegger, said, ‘‘We need to reestablish with the US a relationship of trust, which has certainly suffered from this.’’
France, which also vocally objected to allies spying on each other, asked that the issue of reinforcing Europeans’ privacy in the digital age be added to the agenda of the two-day summit. Before official proceedings got underway, Merkel held a brief one-on-one with French President Francois Hollande, and discussed the spying controversy.
The Europeans’ statements and actions indicated that they had not been satisfied with assurances from Washington. On Wednesday, White House spokesman Jay Carney said Obama personally assured Merkel that her phone is not being listened to now and will not be in the future.
‘‘I think we are all outraged, across party lines,’’ Wolfgang Bosbach, a prominent German lawmaker from Merkel’s party, told Deutschlandfunk radio. ‘‘And that also goes for the response that the chancellor’s cellphone is not being monitored — because this sentence says nothing about whether the chancellor was monitored in the past.’
‘‘This cannot be justified from any point of view by the fight against international terrorism or by averting danger,’’ Bosbach said.
Asked Thursday whether the Americans had monitored Merkel’s previous communications, White House spokesman Jay Carney would not rule it out.
‘‘We are not going to comment publicly on every specified alleged intelligence activity,’’ he said.
But while the White House was staying publicly mum, Carney said the Obama administration was discussing Germany’s concerns ‘‘through diplomatic channels at the highest level,’’ as it was with other US allies fearful of alleged spying.
In the past, much of the official outrage in Europe about revelations of US communications intercepts leaked by former NSA contract worker Edward Snowden seemed designed for internal political consumption in countries that readily acknowledge conducting major spying operations themselves. But there has been a new discernible vein of anger in Europe as the scale of the NSA’s reported operations became known, as well as the possible targeting of a prominent leader such as Merkel, presumably for inside political or economic information.