Police in London have arrested four men suspected of spying on members of the Jewish community on behalf of Iran, authorities said Friday.

In a statement, the Metropolitan Police Service said the suspects — one Iranian national and three individuals with dual British-Iranian citizenship — were detained on suspicion of assisting a foreign intelligence service.

The arrests took place shortly after 1 a.m. at several locations in and around north London. The suspects, aged 22, 40, 52 and 55, are believed to have been gathering intelligence on specific sites and individuals connected to the Jewish community.

Police said the investigation is ongoing and forms part of efforts to counter suspected foreign espionage activities in the United Kingdom.