There can be little as nauseating as the hypocrisy coming from Iran over the conference it has organised on the Holocaust. With spurious objectivity and mendacious intent, Manouchehr Mottaki, the Foreign Minister, said that the aim was not to deny or confirm the Nazi killing of six million Jews, but to create an opportunity for thinkers “who cannot express their views freely in Europe about the Holocaust”. He was, presumably, referring to the legal ban in Germany, Austria and France on those who publicly deny that the killings ever happened — ludicrously elevating these few deluded individuals to the rank of “thinkers”.

At least, however, they will find themselves in congenial company in Tehran, where participants include David Duke, the former Louisiana congressman who said it was “scandalous” that the Holocaust could not be discussed freely, and Georges Thiel, a French writer convicted of publicly asserting that the Holocaust was “an enormous lie”. The conference’s director expressed astonishment at outside criticism, saying that he was hoping to provide “an appropriate scientific atmosphere”. This comes only months after Iran officially sponsored a display of cartoons about the Holocaust, supposedly in response to the “insulting” Danish cartoons of the Prophet Muhammad. When even the country’s President, Mahmoud Ahmadinejad, is on record as saying that the Holocaust is a “myth”, there must be some wonder at the Iranian meaning of the words “appropriate” and “scientific”.

As even embarrassed Iranians realise, the conference is a disgrace, a grotesque attempt to relativise, if not deny, a crime against humanity. Far from giving those in the Middle East a chance to discuss this historical event (a chance all too rarely given in their own countries), the organisers have already censored the proceedings by denying a visa to an outspoken Palestin-ian lawyer who said that denials of the “monstrous horror” harmed the Palestinian cause.

He is right. For it is not simply that the denial or playing down of the Holocaust will, as Amos Oz, the liberal Israeli writer, said, “be received with revulsion and disgust everywhere in the world”; it makes the terrible mistake of justifying criticism of Israel by denying the historical fact so crucial to the state’s founding. The more thoughtful Palestinians have already understood that the refusal to acknowledge the wartime persecution of the Jews gives credibility to the assertion that critics of Israel are motivated by anti-Semitism. Iran’s President simply proves the point. He has labelled Israel a “tumour” that should be “wiped from the face of the Earth”.

Mr Mottaki has revealed the real intention. “If the official version of the Holocaust is thrown into doubt, then the identity and nature of Israel will be thrown into doubt”. With such crass statements from their supporters, the Palestinians must worry that their case will never be understood. In fact, the truth or otherwise of the Holocaust is of no concern to Iranian hardliners. They are using the issue because of its emotive value — in Israel, Europe and especially in the US. Nor is the timing coincidental. The hardliners are determined to rally domestic support for their defiance on the nuclear issue and to sabotage any dialogue with America on Iraq. What better way to achieve isolation than to deny one of the most shameful events in Western history?