They said the Walter-Lübcke School in Wolfhagen, Hesse last week received a threatening letter signed “NSU 2.0”, in reference to a neo-Nazi cell that murdered immigrants between 2000 and 2007.
“Police took the threat seriously and in close agreement with the school's management took necessary measures,” police from the state of Hesse told AFP.
No suspicious objects were found at the school, police said, adding that there was no danger for staff or students.
Lübcke, a member of Chancellor Angela Merkel's party who backed her pro-migrants stance, was shot dead by 47-year-old Stephan Ernst in 2019 in what was believed to be Germany's first far-right political assassination since World War II.
Ernst was sentenced to life in prison last Thursday, after the prosecution argued that he had been motivated by “racism and xenophobia”.
Interior Minister Horst Seehofer has declared far-right extremism the “biggest security threat facing Germany”.