Mr Brown wrote on a blog that the Shoah was “a Holocaust that we deny and belittle at our peril. Yet too many in Israel now turn a blind eye to their countries [sic] creation of a ghetto for an entire Palestinian nation and seem to think it is OK because it is not happening to Jews.”
“Frightening how so many #Jewish settlers have decided #Palestinians aren’t people like them,” Mr Brown also tweeted. “What does that remind you of?”
Ian Middleton, parliamentary candidate for Banbury, claimed Palestinians were “treated like the Jews were during WWII”.
In another tweet, he said of Palestine: “Has the world forgotten the #Holocaust?”
During the row over Ken Livingstone's comments about Hitler and Zionism in April 2016, Mr Middleton tweeted: “There WAS a Nazi-Zionist agreement”.
At the same time, Catherine Rowett, now parliamentary candidate for Norwich South and a Green MEP, said: “Political bullying now consists in pretending that legitimate political criticism of a brutal regime is antisemitism.”
Kirsten de Keyser, parliamentary candidate for Holborn and St Pancras, tweeted during an episode of BBC debate programme Question Time in 2015 that an audience member had “clearly been set up by the Beeb to field the Jewish question”.
Ealing North parliamentary candidate Jeremy Parker wrote “stop the smears. End the witch hunt” when he retweeted a petition defending Shahrar Ali, Green candidate for Bethnal Green and Bow, after he was revealed to have compared one of Israel’s 2009 offensive on Gaza to the Shoah in a speech he gave three days before Holocaust Memorial Day.
When footage of the speech emerged as Mr Ali ran for leadership of the party last year, as part of his response he tweeted: “IHRA definition and examples [are] politically engineered to restrict criticism of Israel’s heinous crimes upon the Palestinian people and actually beginning to succeed in that.”
Mr Ali also proposed a motion at the Green Party conference last year calling for the party to resist adopting the IHRA definition of antisemitism.
Darren Parkinson, parliamentary candidate for Bradford West, posted a picture of himself with a buzz-cut on Facebook in 2016. One of his friends commented “Auschwitz head”, to which Mr Parkinson replied: “That was my plan!”
Nathan Rae, who was the prospective parliamentary candidate for Manchester Withington until being dropped just after the election was called branded ultra-zionist Jews on a Louis Theroux documentary “Zionist crazies” who “sound more like Nazis than I expected”.
On a separate occasion, he tweeted during a discussion about spitting on the street, “just because something is disgusting does not mean it should be banned. Jews were considered disgusting once. #hitlercard”
Councillor Simon Bull, parliamentary candidate for Bournemouth West, has written articles for the Dorset Eye, a blog which earlier this year claimed Countdown presenter Rachel Riley works “for (or with) the Israeli state” and warned that “at some point another Jo Cox moment will happen.”
Board of Deputies President Marie van der Zyl said the candidates had “crossed a clear line in comparing Israel to Nazi Germany and blaming the victims by claiming the legitimate anxiety of the Jewish community about the rise of antisemitism is fabricated.”
She urged the Greens “to suspend the candidates in question immediately.
“It should also, without further, delay sign up to the internationally recognised definition of antisemitism which gives a clear guide to what is anti-Jewish racism.”
A Green spokesperson said the party “utterly condemns and is committed to confronting antisemitism”, adding: “Any new allegations that come to light will be looked into. The Green Party has a robust complaints procedure which is conducted without prejudice.
“The current and previous leadership have regularly advocated signing the IHRA definition of antisemitism and a process of internal discussion is under way.”
Mr Brown denied that he had ever made any comparison between Nazi Germany and Israel and said he considered himself “a critical friend of Israel”.
“I remain a committed anti racist campaigner and as such I will vigorously defend any accusations of anti-semitism,” he said.
Mr Middleton, Ms Rowett and Ms de Keyser were contacted for comment.
CORRECTION: An earlier version of this story stated Shahrar Ali gave his speech on Holocaust Memorial Day. This has been amended
