Iranian President Hassan Rouhani on Saturday called Israel a "cancerous tumor" established by Western countries to advance their interests in the Middle East.
Iran's leaders frequently condemn Israel and predict its demise, but Rouhani, a relative moderate, rarely employs such rhetoric.
Addressing an annual Islamic Unity Conference on Saturday, Rouhani said, "One of the ominous results of World War II was the formation of a cancerous tumor in the region." He went on to refer to Israel as a "fake regime" set up by Western countries.
Prime Minister Benjamin Netanyahu responded later Saturday, saying "Rouhani's slander, which calls for the destruction of Israel, proves yet again why the nations of the world need to join in the sanctions against the Iranian terrorist regime which threatens them."
Iran supports militant groups like Hezbollah and Hamas that are pledged to Israel's destruction. Iran has never threatened to attack Israel, but has vowed to retaliate if it is attacked. Israel views Iran as an existential threat.
Rouhani further said that the United States cultivates close ties with "regional Muslim nations" to protect Israel, an apparent reference to Iran's regional rival Saudi Arabia and the kingdom's Sunni Arab allies. He said bowing to American pressure amounts to "treason."
He added, however, that Iran was prepared to defend Saudi Arabia from "terrorism and superpowers."
"We do consider you as a brother," he said. "We do consider the people of Mecca and Medina our brothers," he said, referring to Islam's two holiest cities, in Saudi Arabia.
The Iranian leader further urged Muslims worldwide to unite against the United States, instead of "rolling out red carpets for criminals."
"Submitting to the West headed by America would be treason against our religion ... and against the future generations of this region. We have a choice to either roll out red carpets for criminals or to forcefully stand against injustice and remain faithful to our Prophet, our Quran and our Islam," he said.
Hamas leader Ismail Haniyeh addressed the conference via video, and said all Arab countries "must outlaw any attempt to normalize relations with Israel. … The Zionists are out No. 1 enemy."
Elsewhere, Iranian Foreign Minister Mohammad Javad Zarif reportedly left a hotel in Rome on Friday, ahead of a speech by Knesset Speaker Yuli Edelstein.
Both officials addressed an international conference on dialogue in the Middle East.
"Israel has no border with Iran, but Iran is looking to create a border with Israel by establishing itself militarily in Syria, Lebanon and the Gaza Strip. Israel will act against those who undermine our existence," Edelstein told the audience.
In a Facebook post, Edelstein later said that Zarif left the conference hall in the hotel as he was gearing up to deliver his speech.
"He can't hear the truth, and deal with the fact that he represents a country that spreads hate and terror throughout the world," Edelstein wrote.
Prior to the conference, Edelstein met with Italian Foreign Minister Enzo Moavero Milanesi and several other top Italian officials.
"Iran is a dangerous country that threatens not only Israel but the entire world, not only with missiles but also with malicious propaganda and by spreading hatred and lies," Edelstein said during his meeting with Milanesi. "It is regrettable that Italy insists on maintaining trade ties with Iran," he said.