Police patrols have been stepped up in Jewish neighbourhoods following the most intense period of antisemitic incidents to have been recorded in Britain in decades.

Safety fears are so acute that reports have emerged of members of Britain's Jewish community fleeing the UK with antisemitic incidents running at around seven a day this year.

Around 270 cases have been reported in 2009, according to figures compiled by the Community Security Trust (CST), the body that monitors anti-Jewish racism, with most blamed on anti-Israeli sentiment in reaction to hostilities in Gaza. Attacks recorded during the first Palestinian intifida of the late 1980s averaged 16 a month.

Scotland Yard is understood to have placed prominent Jewish communities on heightened alert, while the Association of Chief Police Officers' national community tension team is responding to intelligence by issuing weekly patrol directives to chief constables instructing them of threats to Jewish communities in their areas.

Incidents recorded by the CST include violent assaults in the street, hate emails and graffiti threatening "jihad" against British Jews. One disturbing aspect involves the targeting of Jewish children. A Birmingham school is investigating reports that 20 children chased a 12-year-old girl, its only Jewish pupil, chanting "Kill all Jews" and "Death to Jews". In another incident a Jewish schoolgirl reported being bullied at a non-Jewish school because of the Gaza conflict.

CST spokesman Mark Gardner said the current fear of persecution was so profound that some members of the Jewish community were seeking to emigrate to countries where they felt more secure, such as Israel, the United States or Australia. "I know two families, one of which has already moved and the other which is in the process of moving, who don't see the point of putting up with this," he added.

This week the CST will publish its annual report on antisemitic incidents for 2008, which will reveal that around 550 were recorded in the UK last year, slightly less than the record of 594 in 2006, when Israel and Lebanon waged a brief but bloody war.

Veteran director and actor Steven Berkoff recently explained the anti-Israeli reaction over Gaza by saying: "England is not a great lover of its Jews. Never has been".

Some within Britain's 350,000-strong Jewish community accuse the government of not doing enough to condemn the increase in antisemitism. However, the Board of Deputies of British Jews said it had recently received a letter from the communities minister, Hazel Blears, stating that she was "deeply concerned about the dramatic rise in antisemitic attacks in the UK".

Mark Frazer, spokesman for the Board of Deputies, said: "We are seeing an unprecedented level of attacks directed at the Jewish community, both physical and verbal. It is incumbent upon us all to isolate and marginalise those who would derail the legitimate political debate with an extremist and hateful ideology." Recorded attacks have centred on the Jewish communities of Golders Green and Hampstead Garden Suburb in north London.