Some countries boycotted the conference because of Mr Ahmadinejad
Iran's President Mahmoud Ahmadinejad has returned home to what has officially been described as a sensational welcome.
This follows his controversial speech at a UN anti-racism conference.
European delegates walked out when he described Israel as a racist state. France called his address a "hate speech", while the US called it "vile".
Some countries had boycotted the conference because the Iranian president was appearing.
But Iranian state media described Mr Ahmadinejad as the superstar of the conference.
World affairs correspondent, BBC News website
The one issue that never seems to go away when conferences of this kind are held is the Israeli-Palestinian one.
A document has been already been agreed among those governments attending and you have to read it quite closely to detect the tremors remaining from the earthquakes in discussions that went before.
But enough contentious issues remain and the result is a boycott by the US, Israel, Germany, Italy, Australia, Canada and New Zealand.
According to Iran's official news agency, a crowd gathered at Tehran airport from the early hours, reports the BBC's John Leyne in Tehran.
When Mr Ahmadinejad emerged they created what the agency called a "very sensational scene" to welcome him home.
One pro-government paper said the president had shot the last bullet into the brain of the West.
Government opponents have chosen, or been prevented, from making any open criticism, our correspondent adds, although some papers hinted at their scepticism by describing his speech as "controversial".
Mr Ahmadinejad spoke on Monday at the start of the five-day UN conference in Geneva.
Jewish migrants, he said, had been sent from Europe and the US after World War II "in order to establish a totally racist government in the occupied Palestine".
He continued: "And in fact, in compensation for the dire consequences of racism in Europe, they helped bring to power the most cruel and repressive racist regime in Palestine."
His comments prompted a walk-out by delegates from at least 30 countries, and a raft of condemnation from Western officials.
Diplomats who remained, however, applauded as Mr Ahmadinejad continued his address.
UN Secretary General Ban Ki-moon expressed dismay at both the boycotts and the speech, saying Mr Ahmadinejad had used it "to accuse, divide and even incite".