Russian President Vladimir Putin talks with German Chancellor Angela Merkel in 2014. REUTERS/Kevin Lamarque

A Russian-born 13-year-old girl, known only as Lisa F, claimed in January last year that she was kidnapped and raped by three refugees while living in Berlin.

The story provoked a huge response on social media. Russian news outlets ran with the news before the police could complete their investigation. It also sparked protests in Berlin, where campaigners condemned Angela Merkel's refugee policy.

The story went so far that Russia's Foreign Minister, Sergei Lavrov, accused the German government of trying to cover it up and of "sweeping problems under the rug." In return, Berlin warned Russia not to exploit the case for propaganda.

Just days after the report, Berlin police concluded their investigation and said the girl had spent the 30 hours in which she was reportedly kidnapped with people she knew — and that a medical examination had shown she had not been raped. They did open an investigation into two suspects.

This did not stop Russian media from warning repeatedly over migrants raping women and children in Europe. Most worryingly, many German Russians still refused to believe the German police or government after the story was disproved.

The so-called "Lisa-case" is one of thousands of online stories linking refugees in Europe to criminal activity, including rape, assaults, and robberies. Fuel is thrown on these embers by groups on social media and blogs. Behind it all is what politicians and experts are calling a growing Russian propaganda campaign aimed at destabilising Europe.

An EU official with knowledge of the matter, who asked to remain anonymous due to the sensitive nature of his work, talked to Business Insider about the disinformation campaign emanating from the Kremlin. The Kremlin did not immediately respond to our request for comment over email.

The Lisa-case shows how the disinformation works from the bottom up, the EU official explained. In this case, a local story garnered so much attention on social media, that it was picked up by Russian state media and eventually relayed to the top people in the Russian administration, creating a diplomatic spat.

The other way disinformation campaigns are decided on is "from the top down," the source said, which entails weekly meetings between the Russian administration and the head of Russian media. "So there, it’s like giving them the narrative for the general messaging they should use from top to down," our source said.

It’s not only the traditional media, it’s also the fringe media, it’s also the trolls, it’s also the NGOs ...

The Russian state-controlled media is only one of the many ways the pro-Kremlin messages are spread though. The media sources used in Europe for Russia's disinformation campaign are numerous and depend on the country.

In the Baltic states, where there is a large number of Russian speakers, many already watch and read normal Russian state TV and news sites.

In the rest of Europe, our source explains, the propaganda comes from "strange websites" that try and convince the readers that the mainstream media is lying to them. And although their readership is quite small, they are large in number and have a lot of social media engagement.

The EU official also added that their network was so wide-ranging that to keep track of every single outlet is impossible. The source described the scale of the propaganda:

"Unfortunately we do not really have a complete overview of all the channels they use, because really we are talking about thousands and thousands in dozens of languages. It’s not only the traditional media, it’s also the fringe media, it’s also the trolls, it’s also the NGOs, it’s also the diplomats who spread pro-Kremlin information. It’s simply too many channels. It’s quite hard to describe all the things. I’m not sure anyone in the world has a complete overview of it."

Angela Merkel is 'enemy number one' for Russian propagandists

For months now, experts on Russian propaganda in Europe have sounded the alarm bell on the country's increasingly numerous and perfidious attempts to manipulate public opinion.

Both NATO and the European Union have in the recent years set up task forces to try and deal with the growing threat but our source says it's not enough, and that the Russian disinformation campaign urgently needs to become part of the everyday public debate.

And it's not just experts, high-ranking government officials in Germany, Sweden, Denmark, and Czech Republic have also issued stark warnings. In November, Bruno Kahl, the head of Germany’s foreign intelligence service, said that the German elections could be targeted by Russian hackers focused on spreading misinformation.

"We have evidence that cyber-attacks are taking place that have no purpose other than to elicit political uncertainty," Kahl told Süddeutsche Zeitung. "The perpetrators are interested in delegitimising the democratic process as such, regardless of who that ends up helping. We have indications that [the attacks] come from the Russian region."

The East StratCom Task Force, set up by the EU in 2015 to combat Russian disinformation, said over the past 15 months it has found "more than 2,500 examples in 18 languages of stories contradicting publicly available facts, multiplied in many languages and repeated on a daily basis."

Merkel and Putin in 2012. REUTERS/Maxim Shemetov The East StratCom Task Force also found that the German Chancellor had come under increasing attacks last year and warned that she would face an even broader campaign ahead of the federal elections in Germany later this year.

"It is becoming quite obvious that she is now the target number one for them... the enemy number one is definitely Angela Merkel," our EU source confirmed. "She stands for everything that the Kremlin stands against, co-operation of the EU, and cooperation of the EU with the US, so yes she’s the strongest enemy they have at the moment in the West."

The Russian intelligence services are looking for weaknesses that would make countries vulnerable to manipulation. Those weaknesses can be tensions in the political landscape, populist, far-right or Eurosceptic parties, resurging historic social divisions, or deep dissatisfaction within parts of the population not being addressed by the government.

The refugee crisis in Germany became a pressure point for the Kremlin as Germans became increasingly resentful of hundreds of thousands of refugees arriving in the country over the course of a few months. Other issues exploited by propagandists are the Ukraine conflict, NATO, and the war in Syria.

A woman holds a picture of German Chancellor Angela Merkel as migrants set off on foot for the border with Austria from Budapest, Hungary, September 4, 2015. REUTERS/Bernadett Szabo But immigration is the key focus. "The refugee crisis is probably the most exploited [theme] in the European member states because it proves to be the most divisive thing. They are always looking for divisions. When you create more divisions then you actually weaken the enemy," our EU source said.

Rise of populism is helping Russia's 'war with the West'

The biggest refugee crisis in Europe since WW2 has been accompanied by a spike in support for populist parties all over the continent. Considering most of those populist parties are deeply Eurosceptic, their rise to power would prove a windfall for Russia's aim to destabilise the EU.

In March, the head of the anti-immigration Party for Freedom, Geert Wilders, who was condemned for discrimination last December, stands a chance of getting into power in the Netherlands. In May, France will elect a new president and, although polls are still showing the head of the far-right Front National party Marine Le Pen as losing in the second round of the elections, her poll numbers keep rising.

Finally, although Germany's federal election in September is seen as one of the most important one in years, the risk of a far-right party coming into power is very low. But, the public opinion on Merkel's refugee policy has turned increasingly negative and the huge amount of fake or partially fake news blaming refugees for various crimes might be at least partly responsible.

French far-right National Front party leader Marine Le Pen, second right, poses for photographers with Dutch far-right Freedom Party leader Geert Wilders, right, Austria's Secretary General of the Freedom Party Harald Vilimsky, second left, and Federal Secretary of Italy's Northern League Matteo Salvini after a meeting of EU far-right parties at the European Parliament in Brussels, in 2014. AP Photo/Geert Vanden Wijngaert "Obviously it is very hard to focus on direct influence but we can also just have a look at the facts, and the facts are quite worrying," the EU official said.

The source added that there were three referendums in the EU in 2016: The referendum on leaving the EU in Britain, the EU-Ukraine association agreement, and the Italian constitutional referendum. The outcome of each was not in the interests of the EU and played into the Kremlins desire to unsettle.

No one can actually tell how much influence the Kremlin's disinformation campaign is having on the public opinion in the EU. What is being observed is that the Russian leadership is actively trying, through various means and channels, to promote certain anti-EU political forces in Europe and shape public opinion.

Russia's strategy to "weaken the opponent," in this case Europe, is "what became the disinformation campaign, the aim of it is to weaken and destabilise the West, because it’s much easier to have 30 weaker opponents than one big one," our source said.

"So any event, any chance to divide and destabilise the West is exploited. It goes hand in hand with the political aim of the current Russian regime. They see themselves as being in a war with the West."