A charity that monitors antisemitism and provides security for British Jewish groups has said the Gaza conflict that broke out in May resulted in its highest recording of anti-Jewish hate incidents.

The Community Security Trust (CST) recorded 1,308 such incidents nationwide between January and June 2021, a 49% increase on the same period in 2020 and the highest recorded in the first half of a year.

CST said the increase had been fuelled by antisemitic reactions to the escalation of violence in Israel and Gaza, similar to that recorded in 2014 as a result of flare-up in conflict.

“This year British Jews have suffered levels of hatred that were worse than anything seen in recent decades. Some of the abuse and harassment targeting young people in particular was disgraceful,” said CST’s chief executive, Mark Gardner. “Looking ahead, CST will keep doing everything that we can to protect our Jewish communities, and to give them the security and comfort that they need.”

CST recorded a monthly record of 639 antisemitic incidents in May, accounting for 49% of all those recorded in the first half of 2021, and on its own a record six-month tally for every year before 2017.

There was also a huge surge in schools, with 130 anti-Jewish incidents recorded, the most in the first half of any year and an increase of 491% on the 22 recorded in the first six months of 2020.

The most common type of language and imagery used in the latest incidents referenced the conflict in the Middle East, demonstrating anti-Zionist political motivation, CST said.

Forty-three incidents directly compared Israel with Nazi Germany, and the terms “Zionism” or “Zionist” were employed in 68 incidents, often as euphemisms for “Jewishness” and “Jew”. Offenders used far-right or Nazi-related discourse in 277 incidents.

The surge in incidents also coincided with the relaxation of Covid-19 restrictions and continued a pattern in which the peaks and troughs of recorded antisemitism corresponded with the severity of governmental restrictions on public or collective activity.

CST received reports of 89 incidents in January 2021, the lowest monthly figure since December 2017, when there were 86 incidents.

The CST said it was possible that the loosening of social regulations, coinciding with the conflict in Israel and Gaza – a subject that triggers strong emotional responses – had provided people with a potential release from months of lockdown-induced frustration.

The charity also said the pandemic had led those who wished to spread anti-Jewish hate to find new ways of doing so. CST received 13 reports of video-conferencing events being hijacked with antisemitic material in the first half of 2021.

These “Zoombombings” were unheard of before the Covid-19 outbreak, it said, but quickly became a method by which “antisemites could take advantage of the new social reality”.

Mark Hamilton, the National Police Chiefs’ Council lead for hate crime, said it was depressing to hear of the incidents of violence and the threats made to UK communities, who “clearly have no involvement in the events unfolding in another continent”.

“It should not be necessary for UK Jewish citizens to demand that their security and peace is protected. It is our collective responsibility,” he said.