Antisemitic hate speech targeting journalists on Twitter has dramatically increased in the run up to the US presidential campaign, according to the Anti-Defamation League.

The human rights group, which monitors anti-Jewish feeling in the US, said it had established a “task force” to monitor the marked increase in the number of antisemitic tweets directed at journalists over the past year.

In a study, the task force found that the 10 most harassed journalists online were all Jewish, including writers Ben Shapiro, Yair Rosenberg and Bethany Mandel.

By analysing keywords used on social media, it revealed that 2.6 million antisemitic tweets were posted between August 2015 and July 2016.

Of these, more than two thirds of the comments were made by Twitter users who used the terms “Trump”, “nationalist”, “conservative” and “white” to identify themselves.

“The spike in hate we have seen online this election cycle is extremely troubling and unlike anything we have seen in modern politics,” said Jonathan A. Greenblatt, ADL chairman. “Today, extremists are burning up Twitter. We are concerned about the impact of this hate on the ability of journalists to do their job and on free speech, which is why we established this task force.”

The ADL stressed that, while Trump supporters appeared to be responsible for the majority of these online comments, this did not imply that the Republican candidate endorsed the abuse.