The United States remains Iran's "number one enemy" despite a recent nuclear deal with world powers, the chief of Tehran's top clerical body said Tuesday, according to Iranian media.

The Assembly of Experts is among Iran's most influential institutions, comprising 86 elected clerics who appoint and can dismiss the country's supreme leader, led by ultraconservative Ayatollah Mohammad Yazdi, AFP reports.

The nuclear agreement should not "change our foreign policy" of opposition to the United States, "our number one enemy, whose crimes are uncountable," Yazdi said in a speech opening the annual two-day assembly meeting.

"The US and Israel are the source of the situation in the region and [their] goal is to protect the Zionist regime in the Middle East," he was quoted as saying, blaming the two countries for the conflicts in Syria, Iraq and Yemen.

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