Anti-Semitic attacks in Britain have risen since the upsurge of hostilities in Gaza, a group which protects Jewish people said today.
The Community Security Trust (CST) has noted 24 incidents since 29 December, of which 19 were in the capital.
They included an arson attack on a synagogue in north west London on Sunday night.
CST spokesman Mark Gardner said: "There has been a significant rise in the number of anti-Semitic incidents, especially when compared with what is usually a very quiet time of year for racist, anti-Jewish attacks.
"It is a pattern with which we and the police are now sadly familiar, whereby hysteria is whipped up against Israel, and British Jews then suffer a wave of anti-Semitism.
"This is how racist attacks work. You have a grinding level of however many you expect in a year, then these trigger events lead to a sudden surge."
In the attack on the synagogue, in Brondesbury, arsonists tried to smash a window, but failed because of the toughened protective glass.
Mr Gardner said: "Having been thwarted they then appear to have attempted to set the front door alight with petrol, causing some damage to the exterior of the premises. Police, CST and fire brigade attended the scene."
On New Year's Eve, a gang of youths alarmed people in Golders Green, north west London, by trying to enter Jewish shops while shouting "Jew" at individuals.
Nearby, a Jewish man was pulled from his car and assaulted by three men, but not seriously hurt.
The CST has also noted anti-Semitic graffiti in Jewish areas across London, with slogans sprayed on walls including "Kill Jews".
Most of the five incidents outside London were in north west England, including graffiti on one synagogue, anti-Semitic hate mail sent to another one, and "Hamas HQ" graffiti on a Jewish building in Manchester.