BERLIN, Germany — A German official has hailed the US Senate's announcement of a “major review” of America's clandestine surveillance programs as the first sign Washington has grasped the seriousness of the threat to US-German relations posed by the National Security Agency (NSA) spying scandal.

“If we want to return to a relationship based on trust, it will require serious effort,” Peter Schaar, Germany's commissioner for data protection and freedom of information, told the New York Times.

“Officially the Americans said that they respected German law,” he said. “Now we know that was not the case.”

On Monday, California Senator Dianne Feinstein, a Democrat who chairs the Senate intelligence committee, said President Obama is poised to order the NSA to stop spying on the leaders of its allies and offered her first clear condemnation of the surveillance program, the Times reported.

“I do not believe the United States should be collecting phone calls or emails of friendly presidents and prime ministers,” Feinstein said in a statement announcing a “major review of all intelligence collection programs.”

But much of the damage may already be done.

"The decision to review the surveillance policy is a first step to re-establish trust, but we have put several questions to the US embassy and we haven’t received answers on all of them," Interior Ministry spokesman Jens Teschke said in an interview.

Growing evidence that the NSA was tapping the phone calls of German Chancellor Angela Merkel as far back as 2002 has forced the German leader to take a stronger stance on the so-called Edward Snowden affair — joining with French President Francois Hollande to try to force Washington to handcuff its intelligence services.

Merkel's Christian Democratic Union (CDU) and her likely coalition partners, the Social Democratic Party (SDP) agreed to call a special session of parliament to discuss the spying scandal on November 18, Reuters reported.

The most likely outcome of those discussions is an investigative committee with the dubious prospect of ferreting out much about the cloak-and-dagger operations of the NSA, Germany's Tagespiegel says.

But there have already been calls from Merkel's allies and opposition parties to offer Snowden — who is marooned in Russia — political asylum in Germany to allow him to testify.

On Sunday, the Social Democrats' parliamentary chairman Thomas Opperman said in an interview with Das Bild that the investigative committee should seek to interview Snowden, while Christian Ströbele of the Green Party proposed granting him asylum or witness protection, according to Detsche Welle.

Near-daily revelations about the breadth and depth of the NSA's surveillance program have opened a rift in US-German relations that threatens to expand beyond the immediate issue of spying, DW reported.

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Last week, Merkel pushed other European Union leaders not to allow the widening NSA scandal to derail talks over a proposed EU-US free trade pact. But she faces mounting calls from within her own party and the Social Democrats to freeze the talks, the German news agency said.

As an indicator of how tricky negotiations may become, one such call has come from Social Democrat Martin Schulz, the president of the European parliament who supports the EU-US agreement.

"If such events continue, and more news comes out,” he said during an EU summit last week, “I fear that those who are against the free trade agreement in principle will become the majority.”

Analysts agree US-German relations have been harmed.

"Yes, it's a big scandal, probably the biggest since the Iraq War,” says Nina Schick of the British think-tank Open Europe.

“But will it fundamentally change that friendly relationship — the cooperation on international security issues and more important, perhaps, the trade talks that are ongoing? Probably not.”