Both statements are examples the International Holocaust Remembrance Alliance (IHRA) definition of antisemitism cites as potential Jew-hate.
GMB, a union of more than 600,000 members, also found that Mr Gregson breached its code of conduct by “making our business known to unauthorised organisations and the media without prior approval”.
It also referred to “targeted attacks” he allegedly made against a young female employee of the union, which it said were “utterly unacceptable and frankly sinister”.
Mr Gregson was suspended from GMB, and its disciplinary committee will make a recommendation to the central executive committee for his permanent expulsion.
Writing to him on December 21, it said: “The committee believes your conduct has brought the union into disrepute and we do not believe you are an appropriate person to be a member of our union.”
Rabbi Ahron Cohen, of the anti-Zionist Neturei Karta Charedi group, attempted to attend the hearing to speak in support of Mr Gregson, but his evidence was not considered.
In a statement after the hearing, Mr Gregson insisted he was not "a Jew hater".
"What I actually said was that Israel was a racist endeavour. I also said that Israel tends to exaggerate the importance of the Holocaust for its own political ends," he said.
