De Maiziere referred to the fragile security situation in Germany and said his government would work "closely with security organizations of other countries."

"The situation will continue to remain serious in the New Year," the minister said in an interview published in Saturday's edition of the mass-circulation "Bild" newspaper.

Volker Kauder, the head of the Christian Democratic Union (CDU), to which de Maiziere belongs, also said that close cooperation with intelligence services of other countries was needed. These services would have to be "well-equipped" and be capable of collating and evaluating information on possible attacks, Kauder told "Bild."

Munich police raised a terror alarm on New Year's Eve after being given information that terrorists of Iraqi and Syrian origin were planning attacks on the central station of the Bavarian city and at the train station in Pasing, a transport hub in the city's west. Both locations were sealed for several hours on December 31. Visitors and citizens were asked to avoid big gatherings. The terror warning for the city was lifted the next day.

De Maiziere: closer engagement with intelligence from other countries

Constant vigilance

The Munich police became aware of a possible attack in the city on December 23, according to the Bavaria-based daily "Süddeutsche Zeitung." While the possibility of an attack initially seemed to be very limited, authorities received more information on December 31. The German intelligence agency BND and French officials had also communicated the threat of attacks at train stations in Munich.

Speaking in support of cooperation between intelligence services, security expert Rolf Tophoven told German media, "In view of the open spaces and borders in the Schengen area, this cooperation is a decisive factor." According to Tophoven, director of the crisis prevention institute IFTUS in Essen, Germany was a target for the extremist organization "Islamic State" (IS). "The more pressure and defeats the terror group IS faces in Syria in Iraq, the more it will try to bring terror to Europe," Tophoven said, adding that Germany was responsible for assisting the Kurdish militia fighting against IS in Syria.

Constant vigilance was therefore needed, Andy Neumann of the German Federal Office of Criminal Investigation told the "Welt" weekly newspaper. Terror threats in Germany have become normal, he said, adding that terror attacks in the country have not succeeded until now because of "pure luck."

"Our luck will run out one day… That is why it is important to be constantly vigilant," he said.

mg/se (AFP, dpa)