Why Iran takes issue with the Holocaust
When Mahmoud Ahmadinejad was Iranian president, one issue which continually antagonised and offended abroad was his statements questioning the scale of the Holocaust, or whether it had even happened at all.
The new administration under Hassan Rouhani has taken a softer line, but as BBC Persian's Bozorgmehr Sharafedin explains, Iran's position on the Holocaust continues to be controversial.
One key question which President Rouhani kept being asked during his round of media appearances in New York last month was where he stood on the Holocaust.
His responses were careful but did not satisfy everyone that Iran is no longer in the business of Holocaust denial or revisionism.
President Rouhani said the Holocaust was a "reprehensible and condemnable crime".
But as many people listening to his interviews on the fringe of the UN General Assembly pointed out, he did not say whether he concurred with the mainstream acceptance of the Holocaust meaning the killing by the Nazis of six million Jews.
That, his critics say, shows that he has not closed the door entirely on those in the Islamic Republic who claim the number of victims of the Nazi extermination camps has been exaggerated.
'What the Nazis did is condemned," said Mr Rouhani. "But the aspects that you talk about, clarification of these aspects is a duty of the historians and researchers. I am not a history scholar.'
His Foreign Minister, Mohammed Javad Zarif, has been more outspoken.
A US-educated diplomat who has served for years as Iran's representative at the United Nations, Mr Zarif clearly sees how much the issue has damaged Iran's international reputation.
"Iran never denied [the Holocaust]," he tweeted in an exchange with Christine Pelosi, the daughter of Nancy Pelosi, Minority Leader of the US House of Representatives.
"The man who was perceived to be denying it is now gone."
Mr Zarif was clearly referring to Mahmoud Ahmadinejad who, during his presidency, frequently claimed the Holocaust was a myth. But does the departure of Mr Ahmadinejad mean the end of Holocaust denial in Iran?
Ayatollah Khamenei, the Supreme Leader of Iran who decides on the foreign policy, has repeatedly referred to the Holocaust as a distorted historical event and he is still in power.
Iran and Israel had good relations under the Shah. The 1979 Islamic Revolution ushered in a new period of anti-Israel hostility, but this was not accompanied by any attempt to deny the Holocaust.
In fact during the Iran-Iraq war (1980-88), Tehran found many Western films about World War II quite inspiring for the nation and national television was full of programmes sympathising with the victims of the war, including the Jews.
The first Iranian official to cast doubt on the Holocaust was actually Ayatollah Khamenei.
In January 2002, he referred to gas chambers in concentration camps as a story about which its truth was "not clear" and which was being used as "Zionist propaganda" to gain the sympathy of the world.
Mr Ahmadinejad followed this line and in 2005, in his first year in office, called the Nazi extermination of the Jews "a myth".
"The Holocaust used to be something you only read about in history books in Iran," says Mehdi Khalaji, a senior fellow at the Washington Institute for Near East Policy.
"It was Ahmadinejad who brought this term into Tehran's political literature and made it one of the elements of his foreign policy. During his tenure Iran wanted to threaten Israel and it was the safest way."
Meir Javedanfar, an Israeli expert on Iran and the Middle East who was born and raised in Tehran, believes Mr Ahmadinejad made Holocaust denial a key tenet of his foreign policy for two reasons.
"Firstly, he wanted to distinguish himself from his predecessor, Mohammad Khatami, who became a world figure by proposing the idea of dialogue between the civilisations and religions to the UN," he told the BBC.
"Secondly, he thought denying the Holocaust would be an existential blow to Israel. But he didn't realise denying the Holocaust would be perceived as anti-Semitic rather than anti-Israeli.'
During Mr Ahmadinejad's tenure, there were efforts to try to show that Iran was not anti-Semitic.
Probably the most high profile was a very expensive and well-produced Iranian television series, called Zero Degree Turn - which was in essence an Iranian version of Schindler's List.
It was based on a real life story about an Iranian diplomat who saved Jews in 1940s Paris during the Nazi Occupation by giving out Iranian passports and allowing them refuge in the Iranian Embassy.
But Mr Ahmadinejad continued his Holocaust denial rhetoric, despite the international backlash, as he thought he had found the Achilles heel of Israel.
In December 2006 he ordered the foreign ministry to hold a two-day conference to review the Holocaust. Information obtained by the BBC shows many people at the ministry were frustrated by this order.
"Holocaust denial has been common in the Arab world for decades, but Ahmadinejad's ideology was mainly rooted in revisionist scholars in the West," says Mehdi Khalaji.
"That's why the anti-Holocaust conference in Tehran was mainly attended by Westerners and even some neo-Nazis and members of the Ku Klux Klan rather than Islamists."
"Ahmadinejad thought he had managed to put unprecedented pressure on Israel," says Meir Javedanfar. "But he failed to notice he was only making the Israeli stance on Iran's nuclear programme stronger."
President Rouhani and his team have made it clear that they want to put the rhetoric of the Ahmadinejad years behind them, as they attempt to find a solution to the standoff over Iran's nuclear programme.
In an interview with ABC News at the end of September, Iran's foreign minister described the Holocaust as a "heinous crime" and said that the remarks by Ayatollah Khamenei about the Holocaust had been mistranslated and taken out of context.
"Ayatollah Khamenei has called the Holocaust a myth, but it's unlikely that he would deny the foreign minister's claim," says Mehdi Khalaji.
"Ahmadinejad is the scapegoat now. In the Islamic Republic's tradition, officials usually deny their previous statements, not explicitly, but by putting the blame either on translators or reporters. Mistranslation, in Iranian diplomacy, usually means giving up.'