Source: Lu Junming / Costfoto/Sipa USA
"What they see today in social media is hatred," World Jewish Congress head Ronald Lauder told the conference.
Google told the event, officially called the International Forum on Holocaust Remembrance and Combating Anti-Semitism, that it was earmarking five million euros ($A7.85 million) to combat anti-Semitism online.
"We want to stop hate speech online and ensure we have a safe digital environment for our citizens," said French President Emmanuel Macron in a pre-recorded statement.
European organisations accused tech companies of "completely failing to address the issue", saying anti-Semitism was being repackaged and disseminated to a younger generation through platforms like Instagram and TikTok.
Antisemitic tropes are "rife across every social media platform", found a study linked to the conference that was carried out by three NGOs.
Hate speech remains more prolific and extreme on sites such as Parler and 4chan but is being introduced to young users on mainstream platforms, the study said.
On Instagram, where almost 70 per cent of global users are aged 13 to 34, there are "millions" of results for hashtags relating to anti-Semitism, the research found.
On TikTok, where 69 per cent of users are aged 16 to 24, it said a collection of three hashtags linked to anti-Semitism were viewed more than 25 million times in six months.
"There was an Instagram account where the young people in my city posted a lot of anti-Semitic things," 18-year-old Johanna Gosenius told AFP, saying she had been targeted on another site.
In response to the report, a Facebook spokesperson said anti-Semitism was "completely unacceptable" and claimed to be have tightened policies on hate speech and Holocaust denial.
A TikTok spokesperson said the platform "condemns anti-Semitism" and would "keep strengthening our tools for fighting anti-Semitic content".
According to the EU's Fundamental Rights Agency, nine out of 10 Jews in the EU say anti-Semitism has risen in their country and 38 per cent have considered emigrating because they no longer feel safe.
"Anti-Semitism takes the shape of extreme hatred on social networks," said Ann Katina, the head of the Jewish Community of Malmo organisation that runs two synagogues.
"It hasn't just moved there, it has grown bigger there," she told AFP.
Swedish Prime Minister Stefan Lofven has made the fight against anti-Semitism one of his last big initiatives before leaving office next month and has vowed better protection for Sweden's 15,000-20,000 Jews.
Reports of anti-Semitic crimes in the Scandinavian country rose by more than 50 per cent between 2016 and 2018, from 182 to 278, according to the latest statistics available from the Swedish National Council for Crime Prevention.
The Jewish community in Malmo has fluctuated over the years, from more than 2,000 in 1970 to just over 600 now.
In the early 2000s, anti-Semitic attacks in Malmo made global headlines. Incidents included verbal insults, assaults and Molotov cocktails thrown at the synagogue.
In response, authorities vowed to boost police resources and increase funding to protect congregations under threat.
"Once, a girl said about me 'She's Jewish, gas her'," said 21-year-old Mira Kelber of Jewish Youth Malmo.
Mirjam Katzin, who coordinates anti-Semitism efforts in Malmo schools - the only such position in Sweden - said there was "general concern" among Jews in the city.
"Some never experience any abuse, while others will hear the word 'Jew' used as an insult, jokes about Hitler or the Holocaust or various conspiracy theories," she said