German police arrested a man in Berlin and a woman and a man near Cologne on Thursday (4 February) for what they believe may have been preparation for a terror attack in the German capital.

Police raids were also operated in Hannover. Two other men are still being hunted by security forces, which are expected to publish photos on Friday.

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Documents including fake IDs and telephones were seized, but not weapons.

A spokesman for the state prosecutor said that there were "plans for possible attacks in Germany, concrete for Berlin".

According to German media, targets could have included Checkpoint Charlie, a former crossing point between East and West Berlin visited frequently by tourists, and Alexanderplatz, Berlin's central square. Police were deployed on both sides Thursday.

The suspects were under surveillance, and police and intelligence services decided to act after they appeared to stop communicating with each other.

"As they did not speak about the attack, we could fear that their plan was finalised," a security official was quoted as saying by the Tagesspiegel.

The newspaper said that orders for attacks in Berlin were given by Islamic State (IS) leaders, the same who ordered the Paris attacks in November.

One of the two men arrested, a 26-year old Algerian, was already wanted by Algerian authorities for his involvement in IS. The German press agency DPA also said he recently went to Molenbeek, the Brussels neighbourhood where several Paris attackers lived.

According to the Berliner Zeitung, he came from Syria through the Balkans and Bavaria and was registered as a refugee. He was arrested in a refugee centre in Attendorn, 80 km from Cologne.

Critics

The arrest, and the reported use of refugee status, could fuel the controversy over the German government's migration policy.

Germany's intelligence chief said in the Berliner Zeitung Friday that his services received more than 100 tips-off about IS fighters among refugees, and that many of them proved to be defamation.

On Thursday, chancellor Angela Merkel came under more pressure to change the course of her policy.

The leader of the Saxony-Anhalt region, Reiner Haseloff from Merkel's CDU party, said there was "at the moment a loss of control that is no longer acceptable".

A poll published this week by ARD television said that 81 percent of Germans now think that the government doesn't control the situation.

Former chancellor Gerhard Schroeder also critised Merkel on Thursday. In a meeting of his SPD party, he said he would never have used the phrase "we can make it" which Merkel repeated many times since the start of the migrant crisis.

"I would have said: 'We can make it when we are ready to face the challenges'," Schroeder said.