BERLIN (Reuters) - Moscow’s intervention in an alleged rape case involving a German-Russian girl has heightened suspicions in Berlin that it is trying to stir up trouble, with a view to weakening Chancellor Angela Merkel.

File photo of Russian President Vladimir Putin speaking with German Chancellor Angela Merkel at the Tomb of the Unknown Soldier by the Kremlin walls in Moscow, Russia, May 10, 2015. REUTERS/Maxim Shemetov/Files

The case of the 13-year-old, named only as Lisa F., became the focus of political intrigue after she told police that she had been kidnapped in east Berlin last month by migrants who raped her while she was held for 30 hours.

Senior German officials believe Russia is trying to erode public trust in Merkel using immigration, an issue which has badly damaged her opinion poll ratings and divided European Union governments over who should accommodate asylum seekers pouring in over the past year.

By undermining Merkel, who has taken a tough line on the Ukraine crisis, Moscow hopes to destabilize Europe and create a vacuum into which it can project its own power, they say.

“There is a Russian attempt to strengthen disunity in the EU and to work with anti-European, right-wing populist parties,” said one senior official, speaking on condition of anonymity.

The Kremlin could not immediately be reached for comment.

The teenager’s case blew up into a diplomatic row last week when Russian Foreign Minister Sergei Lavrov accused the German authorities of “sweeping problems under the rug”. Berlin warned Moscow not to exploit the case “for political propaganda”.

The Berlin public prosecutor’s office has since said the girl spent the 30 hours with people she knew, and that a medical examination had shown she had not been raped.

But the waters were muddied long enough to allow Lavrov to intervene in the case of Lisa F., who German media say is a dual national who moved with her family to the country in 2004.

“The refugee crisis and the Lisa case have allowed (Moscow) to exploit more strongly groups like Russian Germans, and to play with Germans’ angst and insecurities,” said Stefan Meister of the German Council on Foreign Relations, a think tank.

The case has provoked outrage among Berlin’s Russian community and Russian media have reported extensively on it.

Russians protested in Bavaria at the weekend, after about 700 people had demonstrated in front of Merkel’s office, some holding banners reading “Our children are in danger” and “Today my child, tomorrow yours”.

THE END OF TRUTH

The case has fomented popular anxiety.

“The end of the truth,” ran a headline in the latest edition of Der Spiegel magazine, above a picture of Merkel and Russian President Vladimir Putin.

Spiegel quoted the chief of BfV Germany’s domestic security agency, Hans-Georg Maassen, as saying Russia was using KGB-style “old measures” of misinformation and detribalization.

At the same time, Putin is trying to charm Germans. Last month, he gave an interview to the mass-selling daily Bild, saying he wanted to work with Europe against terrorism.

Meister said this was “to serve the wish among the (German) elite and parts of the population that Russia is showing a readiness to compromise”.

Russia is pursuing its policy of misinformation, as Germany sees it, at a crucial time for the EU. The refugee crisis is stretching it to new limits and EU leaders believe they have just weeks to get their act together.

At the center of the turmoil is Merkel, still the EU’s most powerful leader. If she falters, the risk is Europe falters.

“The aim is to weaken the EU,” the senior German official said. “Moscow is targeting the strongest, most stable country – Germany. Of course it is in the interest of this Russian government to weaken Merkel as the leader of this country.”

Another senior German official added: “The EU cannot allow third parties to split the union.”

Merkel, who enjoyed record high ratings early last year, has looked increasingly isolated as dissatisfaction has grown with her welcoming attitude toward people fleeing conflict and economic hardship in the Middle East and Africa.

A poll last week showed 40 percent of Germans wanted her to resign over her refugee policy.

Merkel’s role in EU relations with Russia is crucial.

“Merkel is, from Putin’s viewpoint, the main problem,” said Meister. Her Social Democrat coalition partners - the party which pursued “Ostpolitik” rapprochement with the Soviet bloc during the Cold War - were more ready to compromise with Putin.

Moreover, the leader of Merkel’s conservative Bavarian allies, Horst Seehofer, is off to Moscow on Thursday to meet him. Politicians across the spectrum in Berlin are worried that Seehofer, who has sharply criticized Merkel for letting in so many migrants, will cosy up to Putin. Seehofer defended the visit on Sunday.

ILLUSION-FREE

Merkel’s relationship with Putin is cold, illusion-free and grounded in a hard-nosed realism born of her own experience growing up in a Soviet garrison town in East Germany. She recognizes that the former Soviet agent respects firmness.

Thus, she was firm in her role as chief mediator in the Ukraine crisis, and has since been implacable in her refusal to ease sanctions against Russia that are intended to punish Moscow for annexing Crimea and supporting separatists in eastern Ukraine.

“Should Merkel fall over the refugee crisis, there would be no hold-up in the EU any more in doing away with the sanctions,” said Meister.

Merkel’s allies are closing ranks around her over Ukraine and Berlin’s technical help for Western airstrikes on Syria, although its jets are not doing any of the bombing.

“Germany must send clear signals to Moscow and stay its course on the Ukraine/Russia conflict and with Syria,” said Roderich Kiesewetter, a foreign policy spokesman for Merkel’s conservatives in parliament. “Only in this way can it be made clear to Russia that constructive, diplomatic cooperation serves both sides.”