President Obama and German Chancellor Angela Merkel in the Oval Office of the White House in 2009. (SAUL LOEB/AFP/Getty Images)

France rejected as implausible assertions by U.S. intelligence agencies Wednesday that they had not collected phone records of millions of European citizens, and a French government spokeswoman said the charges “appear to have been thoroughly substantiated.”

Neither France nor Spain disputed claims by U.S. intelligence that they collaborated with the National Security Agency to gather and share telephone records collected outside their borders. But France said data collection inside its territory by the NSA appeared to be another matter entirely.

The French statement came as European allies struggled to understand and confront questions at home about what their own intelligence agencies were up to, even as they continued to demand explanations from the Obama administration.

As the NSA spying controversy widened, a U.N. spokesman said U.S. authorities have “given assurances that United Nations communications are not and will not be monitored.” Spokesman Martin Nesirky made no reference to reports of past interception programs.

Meanwhile, a senior German official said his government may feel compelled to take harsh measures against the United States, an ally, after revelations that the NSA tapped the cellphone of Chancellor Angela Merkel for years.

“If it should prove true that the NSA listened in on the chancellor, we may as a measure expel diplomats,” German Interior Minister Hans-Peter Friedrich said in an interview with the Rheinische Post newspaper.

On Wednesday, Merkel’s national security adviser and her intelligence chief met in Washington with top administration officials, including national security adviser Susan E. Rice; Lisa Monaco, President Obama’s chief counterterrorism adviser; and Director of National Intelligence James R. Clapper Jr.

The White House characterized the talks as “an opportunity to hear from one another and jointly determine how the dialogue can best proceed in order to provide the necessary assurance and strengthen our cooperation.” The brief statement by National Security Council spokeswoman Caitlin M. Hayden said, “We don’t have any new announcements to make today, but look forward to continuing these discussions in the coming days and weeks.”

In Berlin, Merkel spokesman Steffen Seibert said the meeting would be quickly followed by a U.S. visit by the heads of Germany’s foreign and domestic intelligence agencies. Merkel and French President François Hollande have spearheaded an effort to develop a new code of intelligence conduct within the European Union, and Seibert said Germany wants a no-spying pact with the United States.

Other top German officials said U.S. lawmakers’ anger at some of the spying revelations was a positive sign that the United States may be close to a policy change.

“I am a little bit hopeful that there will be a continuing, open discussion in the United States,” Justice Minister Sabine Leutheusser-Schnarrenberger said in an interview. “I hope that there will be a very engaged debate about privacy on the one side and security on the other.”

She said U.S. officials had approached E.U. justice ministers about signing an agreement to extradite former NSA contractor Edward Snowden, the source of the spying leaks, to the United States should he step foot on their soil. Leutheusser-
Schnarrenberger said she refused to sign because she was not certain that Snowden, who has taken refuge in Russia, had broken any laws and because he might make a good witness in a German parliamentary inquiry.

But Leutheusser-Schnarrenberger said she was also concerned about U.S. reports that European intelligence agencies had collaborated with the NSA in collecting data.

“We also need more facts about security services in European member states, and also perhaps what our secret service, the Bundesnachrichtendienst, has done in the past,” she said. “I’m not only looking at the United States in pointing my finger, I am looking around.”

Domestic finger-pointing in Europe followed congressional testimony Tuesday by Clapper and NSA Director Gen. Keith B. Alexander that recent European news media reports alleging that the NSA spied on 70 million French citizens and 60 million Spaniards were “completely false.” Alexander said the news media had misinterpreted the Snowden-leaked documents, which he said referred primarily to collaborative intelligence programs with those governments to share information that they gleaned from their own monitoring of calls in Afghanistan and other war zones.

That testimony prompted questions Wednesday in Spain, where the allegations that domestic intelligence services had cooperated with their U.S. counterparts prompted opposition politicians to demand clarification from Prime Minister Mariano Rajoy.

Rajoy told parliament that he “took the matter very seriously” and that Spain’s intelligence chief would speak in a closed-door session of an oversight committee to answer questions about the topic. He did not directly respond to Alexander’s allegations.

In France, the daily Le Monde reported Wednesday that the nation’s external intelligence agency collaborated with the United States, starting in late 2011 or early 2012, to provide a window into Internet traffic flowing through underwater cables that surface in France, citing an unnamed senior intelligence official. The cables carry much of the Internet traffic that flows to Africa and Afghanistan.

In exchange, the NSA provides information about areas of the world where France has no intelligence presence, the newspaper reported, citing the same source. Discussions about the precise ­information-sharing arrangement are still taking place, the source said.

But the government in Paris appeared far from willing to accept Alexander’s comments as the sole extent of NSA activities there. “I saw the NSA director’s remarks,” spokeswoman Najat Vallaud-Belkacem told reporters. “More must be done to clarify the practices of U.S. secret services.”

The European intelligence initiative proposed by Hollande last week was based on “the gravity of the [NSA] actions, which appear to have been thoroughly substantiated,” she said. Alexander’s denials about the collection of information on millions of French citizens “do not seem plausible,” Vallaud-Belkacem added.

Beyond the specific allegations, French ire appeared to stem from what officials there described as a lack of high-level U.S. explanation in the months since the NSA scandal broke this past summer.

U.S. officials, who declined to speak on the record about diplomatic matters, said that there have been contacts through intelligence channels but that the European Union was not an appropriate venue for intelligence discussions at a political level.

The officials acknowledged that the kind of extensive, high-level contacts that the French are seeking have not taken place. They said that intelligence relationships were different with every country and that discussions would have to be undertaken one by one. The German contacts this week, officials said, were a first step toward more intensive conversations with other close allies.

Claude Moraes, a British member of the European Parliament, on Wednesday acknowledged ­Alexander’s rebuttal of the charges but complained that “there was an extraordinarily long silence where we had allegations unanswered. . . . There are still serious allegations.” Moraes, who is leading a parliamentary inquiry into the allegations, said, “The trust issue still remains.”

He is part of a group of European lawmakers who are in Washington this week to investigate the spying reports and who met with Alexander and other U.S. officials on Wednesday.

“The point is not what was done in cooperation with the Europeans,” Elmar Brok, a German member of the European Parliament, said in a news conference held by the group, but “spying on Europeans.”

Birnbaum reported from Berlin. Ellen Nakashima in Washington and Colum Lynch in New York contributed to this report.