Germany's justice minister says Facebook and Twitter have months to improve their response to online hate speech or face legal measures.
Heiko Maas says checks show that social networking sites have a poor record of deleting posts that are flagged by users. He says Facebook removes 46 percent of flagged posts and Twitter removes just 1 percent.
Maas told reporters in Berlin on Tuesday that the checks will continue until March and "if it turns out that the removal rate remains so low then we'll take legislative measures."
Despite strict laws against incitement to hatred, harassment and anti-Semitism, Germany has seen a sharp rise in online hate speech.
Last year a man was sentenced to two years and three months in prison for calling for Chancellor Angela Merkel's execution.