Police sealed off German Chancellor Angela Merkel's office to check a suspicious package as ministers gathered for a cabinet meeting in the building early on Wednesday.
Ministers carried on with their regular meeting after police cordoned off area around the Chancellery in central Berlin, a Reuters witness said.
Four plastic yellow postal crates were left outside the entrance, the witness added.
"We are investigating a suspicious package," a spokesman for Germany's Federal Police told Reuters.
Officers were waiting for specialists to inspect the package, he added.
In 2010, police intercepted a package containing explosives sent from Greece to Merkel's office.
Europe has entered 2016 under a state of heightened alert, seven weeks after Islamist militants killed 130 people in shootings and suicide blasts across Paris.
The incident follows a security scare over New Year after police received a tip that militants from Iraq and Syria were planning attacks in Munich.
New Year's sex assaults stoke German migrant debate
German leaders expressed shock over dozens of apparently coordinated sexual assaults against women on New Year's Eve in the western city of Cologne blamed on "Arab-looking men," but warned against anti-migrant scapegoating.
Chancellor Angela Merkel called for a thorough investigation of the "repugnant" attacks, ranging from groping to at least one reported rape, allegedly committed in a large crowd of revellers during year-end festivities outside the city's main train station and its famed Gothic cathedral.
Merkel's spokesman Steffen Seibert said she had called Cologne's mayor, Henriette Reker, to express her "outrage" over the violence, which she said required "a tough response from the state".
"Everything must be done to find as many of the perpetrators as possible as quickly as possible and bring them to justice, regardless of their origin or background," Seibert quoted Merkel as saying.
Police in Cologne said they had received 90 criminal complaints by Tuesday and quoted witnesses as saying that groups of 20-30 young men "who appeared to be of Arab or North African origin" had surrounded victims, assaulted them and in several cases robbed them.
Germany took in around 1mn asylum seekers in 2015, many of them fleeing war-ravaged Syria.
A plainclothes policewoman was reportedly among those attacked.