Islamic State (IS) claimed responsibility for an attack in which a truck ploughed into crowds in a Christmas market and killed 12 people.
"The executor of the operation.. in Berlin is a soldier of the Islamic State and he executed the operation in response to calls to target nationals of the coalition countries," the militant group's AMAQ news agency said on Tuesday.
Meanwhile, police in Berlin will significantly increase security measures in the coming days, with steps such as erecting barriers, after the attack, the president of the city's police said.
Berlin city's interior senator also said that plans for New Year's Eve will go ahead but security steps will be reviewed.