Thank you Angela Merkel German security service BfV reportedly received more than 100 tip-offs that ISIS militants had infiltrated the country among refugees, according to a recent report. The news comes as massive nationwide anti-terror raids took place this week.The head of the German domestic intelligence service (BfV), Hans-Georg Maassen, told a gathering of politicians that the agency had received more than 100 warnings indicating there were Islamic State (IS, formerly ISIS/ISIL) militants staying in Germany as refugees, newspaper Berliner Zeitung reported Friday, without citing its sources.However , some cases of  baseless defamation  were among those tip-offs, Maassen added, according to the newspaper.German security services have remained on high alert since the November terror attacks in Paris which claimed the lives of more than 130 people.Earlier this week, police and security agents all across Germany were scrambled to search for suspects allegedly planning a terror attack in the country, with Berlin seen as the most likely target. Well-known tourist attractions including Alexanderplatz train station and the Cold War-era Checkpoint Charlie could be among the targets of a possible attack, according to preliminary media reports.On Thursday, a police special force unit raided four flats and two businesses in Berlin, detaining four men accused of allegedly having ties to Islamic State. They were suspected of being involved in planning an attack, police spokesman Martin Redlich told RT.German spy chief warns of 1,000+ radical Islamists ready to attack https://t.co/VZn1xRA2oA pic.twitter.com/BlxXGGXHkK  RT (@RT_com) December 13, 2015One of the suspects, a 49-year-old Algerian, was arrested in a three-bedroom flat in Berlin s predominantly immigrant district of Kreuzberg. He was living there on a fake French passport, local media reported, and owned two shops nearby Alexanderplatz and Checkpoint Charlie. Redlich could not confirm the landmarks were the targets, however.The spokesman said police had acted on a tip-off, but he provided no further details.Similar raids also took place in the German regions of North Rhine Westphalia and Lower Saxony. In Berlin alone, 450 police officers were engaged in the operation, German media reported.The main suspect was a 35-year-old Algerian man detained during Thursday s raid in the town of Attendorn. Said to be a possible leader of an IS terrorist cell, he was also being sought by Algerian authorities over allegations he is a member of the terrorist group.He entered Germany in autumn 2015, having traveled the so-called  Balkan route.  At that time, the 35-year-old was registered in Bavaria as a refugee.Both men had been monitored since the end of 2015, after security services had received a tip-off they might be IS infiltrators.Another unnamed 26-year-old Algerian, who also registered as a refugee and lived in a shelter in central Hannover, is suspected by the police to be the cell s communication agent. He is also thought to have possible ties to Belgian Islamists. He has traveled to the Molenbeek district of Brussels, known for harboring jihadists, at least once in recent weeks. Abdelhamid Abaaoud, the mastermind behind the November s Paris attacks, was a Molenbeek resident.Germany took in over 1.1 million refugees in 2015, and fifty-four percent of Germans believe the terror threat in the country is on the rise because of the high number of incoming migrants, according to the latest Spiegel poll. Via: RT