BERLIN (Reuters) - Facebook must stick to German laws which ban Holocaust denial, the Justice Ministry in Berlin said on Thursday after Mark Zuckerberg caused outrage by saying his platform should not delete such comments.

FILE PHOTO: The Facebook logo is displayed on their website in an illustration photo taken in Bordeaux, France, February 1, 2017. REUTERS/Regis Duvignau/File Photo

Zuckerberg’s remarks have fueled further criticism of Facebook after governments and rights groups have attacked it for not doing enough to stem hate speech.

In the interview with tech blog Recode Zuckerberg said he was Jewish and personally found it offensive to deny the Holocaust but he did not think Facebook should delete people’s views.

Officials in Germany, which has enforced a law imposing fines of up to 50 million euros ($58 million) on social media sites that fail to remove hateful messages promptly, made it clear that Holocaust denial was a punishable crime.

“There must be no place for anti-Semitism. This includes verbal and physical attacks on Jews as well as the denial of Holocaust,” Justice Minister Katarina Barley said on Thursday.

“The latter is also punishable by us and will be strictly prosecuted,” Barley said.

A ministry spokesperson said Facebook must adhere to German law and so far there had been no complaints that the firm had violated it.

Social media networks in Germany must delete or lock obvious criminal content within 24 hours of a filed complaint and other reported content must be resolved by the platform within a week.

“Nobody should defend anyone who denies the Holocaust,” tweeted German Foreign Minister Heiko Maas, who introduced the Facebook law in his previous job as justice minister.

Facebook uses automated software and employs around 7,500 workers to spot controversial content and delete entries that violate its policy.

The justice ministry also said that Facebook and other big social media platforms must report to officials by the end of July on how effective they had been in deleting hate messages from their sites.

A Facebook spokesman in Germany referred Reuters to Zuckerberg’s later statement which clarified his comments, saying he didn’t intend to defend the intent of people who deny the Holocaust.

Online anti-Semitism has become a “worrying phenomenon” in Germany, a study by the Technical University in Berlin, which analyzed more than 300,000 entries from Facebook and other online forums, showed earlier this month.

The proportion of anti-Semitic content in German social media rose from 7.5 percent in 2007 to more than 30 percent in 2017, the study showed.

Josef Schuster, the head of the Central Council of Jews in Germany said the study empirically proved that online anti-Semitism was increasing and becoming more aggressive.

“Because words will eventually be followed by deeds. Online anti-Semitism is not virtual, but a real threat,” Schuster said.