Police in Munich evacuated two major railway stations after an intelligence agency warned Germany of an imminent attack, officials said.

Authorities received information that suicide bombers from so-called Islamic State (IS) could target the main station or Pasing station, Bavaria's interior minister said.

Both stations have since reopened, police tweeted.

Cities across Europe have been on alert for a possible New Year's Eve attack.

"I am happy that nothing has so far happened and I hope it stays that way," said interior minister Joachim Herrmann.

Between five and seven militants were thought to be planning an attack, Munich's police head Hubertus Andra said.

Germany's Federal Criminal Police Office alerted Munich police after receiving the tip off from a "friendly intelligence agency" on New Year's Eve, Herrmann said.

Thousands joined celebrations on the Champs-Elysees. Photo: Reuters

Local media reports say the information had come from French authorities.

The city's police said they had called in reinforcements from southern Bavaria and special police units were already operating in the city.

BELGIUM ARRESTS

Security concerns had already caused New Year celebrations to be cancelled or limited in other European cities.

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.

Extra armed police were patrolling in London. Photo: AFP

They are being held for a further 24 hours, prosecutors said. Two other terror suspects were arrested earlier this week.

But the apparent plots to target New Year celebrations in Brussels were not related to the suspected network behind the Paris attacks, the authorities said.

Police seized material during Thursday's raids including computers, phones and materials for playing airsoft - a military simulation game in which players fire replica weapons loaded with plastic pellets.

Separately, Belgian police arrested a 10th suspect over the 13 November attacks in Paris, in which 130 people were killed.

The Belgian national, identified as Ayoub B, was detained on Wednesday during a raid in the Brussels district of Molenbeek. He has been charged with terrorist murder and participation in the activities of a terrorist group.

In Paris, the traditional fireworks display has been called off but thousands of people partied on the Champs Elysees in the biggest public gathering since last month's attacks.

More than 100,000 police were deployed across France.

EXTRA MEASURES

Security was stepped up in other major European cities too, including Moscow, London and Berlin.

Earlier this week, Austrian police claimed a "friendly intelligence service" had tipped them off that major European capitals were at risk of being attacked over the holiday period.

In Moscow, the fireworks were delayed by five minutes and, for the first time, the police closed Red Square - a traditional place for crowds to gather.

London's Metropolitan Police deployed 3,000 officers in the inner city, including extra armed officers.

In Berlin, officials said the security situation remained unchanged despite the alert in Munich.

Backpacks and fireworks were banned and bags searched on the "party mile" leading up to the Brandenburg Gate.

ANKARA 'PLOT'

On Wednesday, Turkish police arrested two suspected IS members over an alleged plot to attack celebrations in Ankara.

State media said they were planning two separate attacks on crowded areas. Suicide vests and explosives were found during police raids.