Iran is calling Israeli allegations that it was responsible for last week's suicide bombing of a bus carrying Israeli tourists in Bulgaria "baseless" and is accusing Israel of carrying out a "terrorist operation."

Israel's deputy U.N. ambassador Haim Waxman says the accusation by Iranian Ambassador Mohammad Khazaee is "appalling but not surprising from the same government that says the 9/11 attack was a conspiracy theory and denies the Holocaust."

Waxman and Khazaee traded accusations during a U.N. Security Council debate on the Mideast on Wednesday.

The bombing killed five Israeli tourists and a Bulgarian bus driver.

Bulgaria's Prime Minister Boiko Borisov said Tuesday that a sophisticated group of conspirators was involved in the bombing. He did not give any nationalities of those believed to be responsible.