A leading Holocaust memorial group has criticised an event run by an Islamic organisation which compares the Shoah to Palestinian suffering.

The Islamic Human Rights Commission's Genocide Memorial Day is also due to hear from Ahron Cohen, leader of the anti-Zionist Neturei Karta sect, who has previously questioned the number of deaths in the Holocaust.

IHRC said the event would coincide with the second anniversary of the "genocidal acts in Gaza" during Israel's Operation Cast Lead.

The group claims Sunday's presentation, taking place at an Islamic Foundation's head office in central London, will hear from victims of what it terms "the Jewish Holocaust".

Karen Pollock, chief executive of the Holocaust Educational Trust, said the event was "nothing more than an attempt to pervert the message of Holocaust Memorial Day to gravely insult both victims and survivors of the Holocaust.

"Ahron Cohen's past comments on the Holocaust have caused immeasurable upset, and the decision of the IHRC to offer him a platform to speak again on this subject is deeply offensive."

National Holocaust Memorial Day, on January 27, remembers the genocides in Cambodia, Rwanda, Bosnia and Darfur alongside the Shoah.

A promotional video for the IHRC event shows an image of people in a concentration camp and states: "A dark memorial. From modern slavery and eradication of native Americans…to Gaza massacre and Nazi concentration camps… our history is full of dark eras."

Manchester-based Mr Cohen, who styles himself "Rabbi", is billed to appear "with messages from Holocaust survivors". In 2006 he spoke at a Holocaust-denial conference in Tehran, organised by Iranian president Mahmoud Ahmadinejad.

He will be joined by pro-Palestinian campaigner Lauren Booth, who was a passenger on a "travelling peace camp" boat which attempted to reach Gaza – and break Israel's blockade – in 2008.

Last August, Iranian-backed Press TV was censured by broadcasting standards body Ofcom after Ms Booth breached guidelines on impartiality by making anti-Israel comments on a show she hosted for the channel.

The IHRC said it would be "proud" to remember "man's inhumanity to man.

"Two years on from the genocidal acts in Gaza, this event combines the past with the present.

"It consists of a variety of short presentations on the world's many victims. This year we will be covering a number of atrocities including the heart-rending plight of the peoples of Hiroshima and Nagasaki, the suffering of the genocide in Cambodia and accounts from the victims of the Jewish Holocaust."

Other speakers are due to include Campaign for Nuclear Disarmament veteran Bruce Kent, who has previously spoken at anti-Israel events, and Gregory Stanton, president of US-based group Genocide Watch.