The U.K.’s largest annual pro-Israel event, “A Night to Honour Israel,” was postponed due to security concerns following several Islamist terror attacks in the country in recent months.

Some 1,000 tickets had already purchased to the late-June event, which brings together Christian and Jewish pro-Israel advocates in the heart of London. The event’s organizers, Christians United for Israel - UK (CUFI UK), said it was a “difficult decision” to postpone the event. 

“Islamic extremists have called for the specific targeting of Christians and Jews during the month of Ramadan, during which our event was set to take place,” CUFI UK Executive Director Des Starritt wrote in an email to supporters.

“Although no specific threat has been received, we have been advised that our event could be a target,” Starritt wrote, adding, “It is with wisdom and not fear that the leadership takes this responsibility for the protection of those that would attend.”

Seven people were killed and 50 were injured in London June 3 in the U.K.’s latest Islamist terror attack, following last month’s suicide bombing during an Ariana Grande concert at the U.K.’s Manchester Arena and March’s attack on London’s Westminster Bridge. British Prime Minister Theresa May has vowed to crack down on the “evil ideology of Islamist extremism.”