Extra police patrols have been dispatched to stations across Barnet after the national terror level threat was raised to severe.
In an e-mail seen by the Times Series, police warned they would have to step up operations in Hendon and Golders Green to reassure the Jewish community.
The note, sent to Chipping Barnet MP Theresa Villiers, said police patrols would start this afternoon, but there is no specific threat towards any community or person in the borough.
The government raised Britain’s terror threat level from substantial to severe over the weekend, because of the threat from militant groups in the Middle East.
It means an attack is deemed to be “highly likely” although there is no intelligence to suggest one is imminent.
The patrols will continue all of this week and the force is delivering a reassurance strategy as pupils return to the Jewish schools tomorrow and Wednesday.