Molotov cocktails were thrown at a synagogue in a western German town, local police said. A Frankfurt rabbi has received death threats over the phone as anti-Jewish comments in social media skyrocketed in connection with the Gaza crisis.

READ MORE: ‘No children left in Gaza!’ Right-wing Israeli mob mocks deaths in anti-Gaza chant (VIDEO)

Three arsonists threw Molotov cocktails at the Bergische Synagogue in the western German town of Wuppertal early Tuesday morning in an attempt to burn it down, the Westdeutsche Allgemeine Zeitung daily reports.

A neighbor phoned the police after seeing flames near the synagogue at about 2:15am.



Police said it found broken bottles by the entrance to the doors of the synagogue and arrested an 18-year old man in connection with the incident.



No one was injured in the attack and there was little visible damage on the outside of the building.



The synagogue, which was built in 1897, was burned to the ground during the Nazi Kristallnacht pogrom in 1938 and then rebuilt.



In a separate incident, a rabbi in Frankfurt am Main received death threats during a phone call last week.



A man, believed to be a Palestinian, threatened to kill 30 Jews if his family in Gaza was harmed, Dieter Graumann, the president of the Central Council of Jews in Germany, told the Frankfurter Rundschau newspaper.

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Both incidents happened amid a backdrop of increasing anti-Semitism in Germany.

According to Monika Schwarz-Friesel, who is leading a research project into anti-Semitism on the internet at Berlin’s Technical University, there has been a huge increase in anti-Jewish sentiment online.



“Hatred of Israel unites writers of all classes. Three percent of letters were anonymous and came from the far-right scene,” Schwarz-Friesel said.



She added that many of the insults were “falling back on old stereotypes”, with people using phrases like “usurer”, “child murderer” and “global conspiracy.”

Schwarz-Friesel examined 14,000 letters sent to the Israeli Embassy in Berlin and to the Central Council of Jews in Germany, but her current project is focusing on anti-Jewish feeling on the internet.



“The Internet has become the primary distribution medium for the new anti-Semitism,” the Technical University said in a statement Monday.



Meanwhile as violence spirals out of control across the Middle East, there has been a spike in attacks on Mosques and against Germany’s Muslim population. The assaults are said to be mainly waged by the far-right radicals.



Attacks on mosques have jumped 50 percent since 2011, the Neue Osnabrucker Zeitung newspaper reported Tuesday. According to the paper, there were 36 such attacks in Germany in 2013.



The situation in Germany is reflected across the rest of Europe. In Brussels four people were murdered outside the Jewish museum in May.



Vladimir Sloutsker, the president of Israeli Jewish Congress, told members of the Knesset and foreign diplomats Monday that the situation facing Jews in Europe is “simply intolerable, unacceptable and inexcusable.”



Meanwhile in Gaza, at least 100 Palestinians have been killed on Tuesday alone after Israel beefed up its military operation, according to local health officials.

READ MORE: Israel intensifies Gaza shelling, warns of ‘protracted campaign’