Ahead of Eintracht Frankfurt's home game against Mainz on Tuesday evening, police in the city have said they will be taking extra measures to ensure security before, during and after the match.

"We are taking into account the abstract threat situation and will have an increased visible presence, including some colleagues carrying machine guns. This is not usually the case," a spokesperson for the Frankfurt police told the SID news agency. She declined to provide further details on how many more police officers than usual would be deployed around the Commerzbank Arena.

It's not yet clear what extra measures could be taken to ensure security at Tuesday's other three games, in Mönchengladbach, Hamburg and Dortmund.

'Every forseeable factor taken into consideration'

A Dortmund police spokesman told Deutsche Welle that they routinely assess and reassess their operations around Bundesliga games based on all of the information available.

"I can't yet say which, if any extra measures will be taken for tonight's game," Dortmund police spokesman Sven Schönberg said. 

"What I can say is that the Dortmund police always take every foreseeable factor into consideration when planning for security operations at Bundesliga matches. There is no 'one size fits all' plan that we pull out of the drawer, but rather, we take all of the foreseeable factors into consideration for the specific game in question."

A press release posted on the Dortmund police department's website said that in light of the "heightened abstract threat situation" they had stepped up their visible presence and other security measures at public events.

Security measures reviewed on an ongoing basis

Hendrik Grosse Lefert, the head of security at the DFB German football association, struck a similar tone.

"The clubs are on their toes and in consultation with their local network of partners, in particular the police, they may choose to implement further necessary measures," Grosse Lefert told the DPA news agency.

He noted that security measures already in place were constantly being reviewed, particularly since the November 2015 Paris attacks, which included two bombings outside of the Stade de France where Germany were playing France in a friendly.

"Even though 100 percent security cannot be guaranteed for every kind of event imaginable, Germany's stadiums are among the safest in the world," Grosse Lefert said.

Show of solidarity

Meanwhile, the German Football League (DFL) has announced that there will be a minute's silence at all nine Bundesliga's matches this Tuesday and Wednesday to remember the victims of Monday's attack in Berlin. A DFL statement said the players would wear black armbands.

DFL president Reinhard Rauball said this was meant as "a show of solidarity with the victims as well as the citizens of our capital city."

Most Bundesliga clubs and many players, as well as other athletes, have taken to social media to express their condolences.

At least 12 people were killed and around 50 others injured, some of them seriously, when a man drove a truck into a crowd at a Berlin Christmas market on Monday night.