Three men aged 24, 25, and 26 were arrested in Harpenden, a town in Hertfordshire, on Sunday evening and taken into custody before being released on bail.
A 25-year-old man was arrested in Stevenage on Monday, while a 26-year-old man and two women, aged 50 and 59, were arrested in a car near Birmingham. They remain in custody in a London police station.
Separately, a 39-year-old man was arrested Tuesday morning in Ealing, west London, under section 41 of the Terrorism Act 2000 and taken into custody. His arrest was in connection with an existing investigation after jars containing a non-hazardous substance were found in Kensington Gardens near the Israeli Embassy on Friday.
The spate of attacks targeting Jewish communities started with four ambulances belonging to the volunteer Hatzola community service being set alight last month in Golders Green, north west London, while Finchley Reform Synagogue also suffered an attempted arson attack earlier this month.
Since the Hatzola attack, 23 people have been arrested, with eight charged with arson-related offenses and 13 remaining in custody or on police bail.
Deputy Assistant Commissioner Vicki Evans, who’s the senior national co-ordinator of Counter Terrorism Policing, said: “Our message is clear, we will not tolerate this intimidation of our communities, and will pursue those responsible.