“We all know there is a danger of attacks in all of Europe and also in Germany and here in Bavaria”.

He added: “It’s a bit weird, though, that we have a terrorist warning and people are firing off their fireworks”.

The “concrete tip” indicated a group of up to seven Islamic State militants was planning a massacre involving suicide bombers targeting train stations in the Bavarian capital.

Police evacuated two Munich stations at around midnight after they were tipped off about a “serious, imminent threat”. The warning remained in place Friday. Evidence that two of the Paris attackers had entered the continent under cover of a wave of Middle Eastern refugees heightened anxieties over the migration crisis.

Germany received a tip hours before midnight that militants from Iraq and Syria were planning New Year attacks in Munich but police could not find the suspects and are not even sure if they exist or are in the country, the city’s police chief said on Friday.

Although an investigation was opened, no explosives were found nor arrests made.

But German investigators, acting on information from “friendly countries” including France, said they have so far failed to substantiate the threat.

Herrmann called on Munich residents to be cautious, but at the same time not to let the warning interfere with their normal lives. On Friday around noon time, some 100 extra officers were still present in the city.

“The Bavarian authorities acted prudently, calmly and decisively, with the support of the federal police”, Germany’s interior minister, Thomas de Maizière, said. French and United States intelligence agencies are said to have named seven Iraqis living in Munich as the potential attackers.

On Twitter and Facebook, Munich police asked people to avoid crowded places amid the ongoing New Year celebrations.

Shortly after the Paris attacks, German police cancelled a friendly soccer game between Germany and the Netherlands in Hanover because of fears of a planned bomb attack.

Mr Herrmann told a news conference that authorities had received “very concrete information” about the attack.

A spokesman said the force had received two “concrete” pieces of information about a possible attack and warned that other locations could still be targeted despite the train station evacuations. “Thanks for staying calm and for your understanding concerning our measures”.

The terror threat in Munich capped one of the deadliest years of militant violence in Europe.

Cities across Europe have been on high alert for a possible New Year’s eve attack.

The authorities in Brussels called off all official events after three people were detained on Thursday in connection with an alleged New Year’s Eve plot.