EU justice ministers met Friday in a bid to combat a rise in hate speech and xenophobia spread through social media as Europe grapples with an unprecedented influx of refugees.
Facebook pledged last month to fight a surge in racism on its German-language network as Germany has become the top destination for refugees, triggering a backlash from the far right.
"We realised in Germany that hate criminality has increased significantly on social platforms," German Justice Minister Heiko Maas told reporters as he arrived for talks in Luxembourg.
Maas was to brief his EU counterparts about talks with Facebook and other sites as well as German initiatives to fight what he said was a European-wide problem.
"If someone calls for killing refugees or burning Jews then this is not covered by freedom of speech. This is a criminal act which will be prosecuted," he said.
"Facebook, Google, YouTube and Twitter have a responsibility to make sure that such things will be deleted. This is not yet sufficiently the case," he said.
For example, nobody understands why Facebook can delete child pornographic images in 24 hours but "not an incitement to kill someone," he added.
But Vera Jourova, the European commissioner for justice, said it was important to strike a balance between hate speech, which "is simply unacceptable," and freedom of expression, which "is one of our core values."
French Justice Minister Christiane Taubira told AFP that France already had a good legal arsenal against hate speech.
"We must verify at the European level that our laws are harmonised to allow us to prosecute with the same effectiveness and severity everywhere on (EU) territory," Taubira said.