Karen Pollock MBE, Chief Executive of the Holocaust Educational Trust, said:
"In 2010, Mr Corbyn presided over an event comparing Israel to the Nazis, at a meeting entitled "Auschwitz to Gaza" on Holocaust Memorial Day.
"In 2011 alongside Mr McDonnell he supported a change to rename the day 'Genocide Awareness Day' excluding the very specific nature of the Holocaust - it was a specific crime with antisemitism at its core.
"In 2012, he chaired an event by the Palestine Return Centre where a speaker referred to the victims of the Holocaust as now being the 'torturers'.
"These are just some of the incidents brought to light in the past few days.
"At the Holocaust Educational Trust, we are constantly having to point out the importance of language. False equivocations, denial and distortion of the Holocaust are incorrect, inappropriate, hurtful and wrong.
"Why in 2018 do we still find ourselves having to explain the offence this causes to not only Holocaust survivors, but to the Jewish community. We expect more from politicians and political leaders.
"To do it once is a mistake, twice perhaps careless, but multiple times? Deliberate. It seems to me that Jeremy Corbyn is a serial offender."