German police have carried out a series of raids, targeting people suspected of posting hate content on social media.
The co-ordinated raids on 60 addresses were the first time the authorities had acted on this issue in such a way.
The aim is to tackle what police called “a substantial rise in verbal radicalism”.
Typical crimes included “glorification of Nazism [and] xenophobic, anti-Semitic and other right-wing extremism”, they said.
Holger Munch, president of Germany’s federal criminal police authority, the Bundeskriminalamt (BKA) said: “Today’s action makes it clear that police authorities of the federal and state governments act firmly against hate and incitement on the internet.”
He said politically motivated hate crime on the internet had increased significantly in the wake of the European refugee crisis.
Last year, Germany took in up to one million migrants and refugees.
“Attacks on refugee shelters are often the result of radicalisation which begins in social networks,” Mr Munch said.
Much of the hate speech took place in a secret Facebook group, police said but Twitter and Google have also been criticised.