"It is disappointing that Mr Ahmadinejad has once again chosen to espouse hateful, offensive and anti-Semitic rhetoric," Mark Kornblau, a spokesman to the US mission to the United Nations, said.

Delegations from Argentina, the United Kingdom, Costa Rica, Denmark, France, Germany, Hungary, Italy and New Zealand also left the room as Mr Ahmadinejad began to rail against Israel.

Israel had already called for a boycott of the speech and was not present when the Iranian leader began his address. Canada had already said it would heed the boycott call.

In his address, Mr Ahmadinejad again took aim at Israel without mentioning the country or Jews by name, referring only to the "Zionist regime".

The firebrand leader, re-elected in disputed June elections, accused Israel of "inhumane policies in Palestine".

"How can the crimes of the occupiers against defenceless women and children... be supported unconditionally by certain governments?" Mr Ahmadinejad said.

"And at the same time, the oppressed men and women be subject to genocide and heaviest economic blockade being denied their basic needs, food, water and medicine?"

A French diplomat said the speech was "unacceptable", adding that European delegations had co-ordinated their action in advance if they found parts of the address unpalatable.

Suggesting there was a Jewish conspiracy, Mr Ahmadinejad added: "It is no longer acceptable that a small minority would dominate the politics, economy and culture of major parts of the world by its complicated networks."

And he accused Jews of seeking to "establish a new form of slavery and harm the reputation of other nations, even European nations and the US, to attain its racist ambitions."

-ABC