London’s Metropolitan Police received reports of the graffiti on Saturday, and are conducting inquiries “to find who is responsible,” officers said on Sunday.

Ruptly (@Ruptly) December 29, 2019

The graffiti – found at a number of locations in the Hampstead and Belsize Park area – depicts a Star of David and the numbers “9.11,” a reference to the conspiracy theory that a Jewish cabal orchestrated the September 11 2001 terrorist attacks in New York. One of the crude messages was spray-painted onto South Hampstead Synagogue.

“We must move heaven and earth to eradicate this racist hatred, which was unimaginable just a few years back,” Hampstead Councillor Oliver Cooper tweeted on Sunday.

Oliver Cooper (@OliverCooper) December 29, 2019

An August report by a Jewish advocacy group found that 892 anti-Semitic incidents were recorded in the first six months of 2019, including 85 assaults. Such incidents have been rising since 2013, and range from harassment on social media to attacks on the street.

The rise in anti-Semitism has been blamed on the far right, on Muslim immigrants, and on Jeremy Corbyn’s Labour Party. The politician was pressured into apologizing after Chief Rabbi Ephraim Mirvis claimed that “a new poison – sanctioned from the very top” had taken root in the party.

While being “very sorry for everything that has happened,” Corbyn noted that these views were also held by now-withdrawn members of other parties, including the Liberal Democrats and Conservatives. Some pundits maintain Corbyn himself was subjected to anti-Semitism allegations because of his opposition to Israel’s policies and unconditional support for Palestine.

The situation is similar across Europe, with an EU-wide survey last year finding that 89 percent of Jews felt that anti-Semitism had increased in the preceding five years. Thirty-five percent of British Jews surveyed said they had considered emigrating to Israel in response.

As council workers power-washed away the graffiti in Hampstead, a knife-wielding attacker broke into a rabbi’s house in upstate New York on Saturday night and stabbed five people with a machete. New York and the surrounding area has been struggling with its own rise in anti-Semitism in recent weeks, and Governor Andrew Cuomo called the knife attack “an act of domestic terrorism.”