A synagogue and several shops in north London have been daubed with anti-Semitic graffiti during the Jewish festival of Hanukkah.
The Jewish holy symbol alongside the numbers "9 11" was spray-painted in red and purple on several premises in the Hampstead and Belsize Park area, including South Hampstead Synagogue.
The graffiti references an anti-Semitic conspiracy theory that Jews are responsible for the 9/11 terror attack.
Police have said they are investigating the racially motivated hate crime after receiving reports of the vandalism at 11.30pm on Saturday.
Conservative councillor for Hampstead Oliver Cooper said he spent Sunday morning patrolling the neighbourhood after "appalled" residents alerted the Community Security Trust (CST) charity, which works to protect the Jewish community.
Mr Cooper told the PA news agency: "My first reaction was shock and horror."I've had to report anti-Semitic graffiti in Hampstead a number of times before, including by a banned neo-Nazi group, but I have never seen anything approaching this extent."
Mr Cooper said he came across the graffiti in nine places, and others also posted photographs of the markings on Twitter.
Labour leader Jeremy Corbyn sent a message of "love and solidarity" to Jewish communities, while shadow Brexit secretary Sir Keir Starmer and Hampstead and Kilburn MP Tulip Siddiq also spoke out against the incident during the Jewish festival.
He tweeted: "How terrible that Chanukah started with a message of hope and on this last day we face antisemitic graffiti in London and horrific stabbings at a party in New York. We stand with all our communities facing hate.
"We send love and solidarity to Jewish communities around the world."
The Metropolitan Police said no arrests have yet been made.Inspector Kev Hailes said: "This is clearly a concerning incident and one we are taking seriously.
"We have liaised with our partners in order to remove the graffiti and various inquiries are under way to find who is responsible.
"Officers will be on patrol throughout the area in order to provide some reassurance to local communities. Please approach us if you have any questions or concerns."
Police have asked anyone who saw anything suspicious on Saturday night to call them on 101.
The incident comes after five people were stabbed at a rabbi's home north of New York on Saturday night.
A knifeman attacked a Hanukkah celebration in Monsey, before fleeing in a vehicle at around 10pm, police said.
The attack appeared to be the latest in a string targeting Jews in the region, including a massacre at a kosher grocery store in New Jersey earlier this month.
Responding to the graffiti in London, the Board of Deputies of British Jews wrote on Twitter: "This is a reminder that antisemitism is still with us. Thanks @CST--UK for reporting to @MPSCamden. We hope action is taken to find & punish the perpetrators. Let's all work to defeat antisemitism in 2020!"