(JTA) — Following the deadly attack on a Jerusalem synagogue and the stabbing of a Jewish man in Belgium, the security unit of British Jewry advised vigilance around Jewish institutions.

The Community Security Trust issued the warning Tuesday in a security bulletin that contained nine instructions to Jewish institutions, including a call to “ensure visible external security patrols take place to deter and detect hostile activity” and immediate reporting to police of any suspicious behavior.

The instructions were issued in the wake of Tuesday’s Jerusalem attack that killed four people, but “also following the stabbing of a Jewish man on his way to synagogue in Antwerp on Saturday,” the bulletin noted.

“CST is not aware of any specific threat to the Jewish community in the UK. However, we urge everyone to remain vigilant and to report and challenge suspicious activity immediately to Police and CST.”

Eric Pickles, Britain’s secretary of state for communities and local government, called CST chief executive David Delew to discuss the Jerusalem attack and express support, CST said.

Across Europe, Jewish communities expressed shock and outrage at the attack.

CRIF, the umbrella of French Jewish communities and organizations, expressed its “horror.” Its president, Roger Cukierman, said that the presence of Hamas, which praised the attack, in the government of Palestinian Authority President Mahmoud Abbas would “disqualify [the legitimacy] of initiatives for unilateral recognition of a Palestinian state.”

The Consistoire, the organ responsible for providing religious services to many Jewish communities in France, convened its council for a session on the attack. The religious body said in a statement that the attack “reached a new level of barbarism” and sent its condolences to the families of the victims.

Rabbi Pinchas Goldschmidt, president of the Conference of European Rabbis, said in a statement, “Jewish communities around the world are united this morning in immeasurable grief.”