Berlin (AFP) - Germany's government commissioner on anti-Semitism has warned Jews about the potential dangers of wearing the traditional kippah cap in the face of rising anti-Jewish attacks.

"I cannot advise Jews to wear the Kippah everywhere all the time in Germany," Felix Klein said in an interview published Saturday by the Funke regional press group.

In issuing the warning, he said he had "alas, changed my mind (on the subject) compared to previously."

Klein, whose post was created last year, cited "the lifting of inhibitions and the uncouthness which is on the rise in society" as factors behind a rising incidence of anti-Semitism.

"The internet and social media have largely contributed to this -- but so have constant attacks against our culture of remembrance."

And he suggested police, teachers and lawyers should be better trained to recognise what constitutes "clearly defined" unacceptable behaviour and "what is authorised and what is not".

His comments came just weeks after Berlin's top legal expert on anti-semitism said the issue remains entrenched in German society.

"Anti-Semitism has always been here. But I think that recently, it has again become louder, more aggressive and flagrant," Claudia Vanoni told AFP in an interview, adding the problem was "deeply rooted" in German society.

Anti-Semitic crimes rose 20 percent in Germany last year, according to interior ministry data which blamed nine out of ten cases on the extreme right.

Vanoni said the proliferation of online platforms that allow people to express extremist views without inhibition while hiding behind screens had fostered the rise in cases.

The arrival in parliament of the far-right AfD, whose leaders openly question Germany's culture of atonement for World War II atrocities, has also contributed to the change in atmosphere, as has the arrival of more than a million asylum seekers, many from Muslim countries such as Syria, Afghanistan or Iraq.

Klein said that while the far-right was to blame for the vast majority of anti-Semitic crime, it was apparent that some Muslims were also influenced by watching certain television channels "which transmit a dreadful image of Israel and Jews".