Regional courts in Potsdam, Magdeburg, Erfurt, Wiesbaden, Hamburg and Kiel received bomb threats on Friday, police said.
The threats were made by email and vowed attacks across Germany.
Germany is on high alert following a series of terror attacks in the country and across Europe.
What we know so far:
- Authorities are combing the premises of the courthouses with dogs.
- Police said the anonymous assailant or assailants had threatened to detonate explosive devices at the various regional courts.
- In Wiesbaden, a suspicious package was discovered at the courthouse. Police have blocked roads in the surrounding area.
- Police are trying to determine the source of the threatening emails.
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On Twitter, police in Wiesbaden said their operation was "ongoing."
Brandenburg police said they had cleared the building but were still investigating the situation. They had to clear out around 200 people before combing the court for explosive devices.
Similar bomb threats have disrupted proceedings at other German courts in recent weeks; the previous threats turned out to be unfounded.
Security tightened after attacks
Security has been tightened at court buildings across Germany, prompted by fatal incidents, over the past three decades.
In 2012, a Bavarian prosecutor was shot dead in a Dachau courtroom by a 54-year-old transport operator after his conviction for failing to pay social security contributions for his employees.
In 2009, a 28 -year-old man holding xenophobic views stabbed to death an Egyptian-educated pharmacist, appearing as a witness, in a Dresden courtroom. Her husband was severely wounded.
In 1994, seven people, including the presiding judge, were killed when a man convicted of assault opened fire with a pistol and then detonated a bomb inside a courtroom in the town of Euskirchen, west of Bonn.
ls, ipj/msh (dpa, AFP)