UN chief excoriates Iran for threats to Israel, Holocaust denial.DUBAI (Reuters) - Without naming Iran, United Nations Secretary-General Ban Ki-Moon denounced his hosts in Tehran on Thursday for threatening to destroy Israel and for denying the Holocaust.

"I strongly reject threats by any member state to destroy another or outrageous attempts to deny historical facts such as the Holocaust," Ban said in his speech to a Non-Aligned Movement (NAM) summit in the Iranian capital.

"Claiming that Israel does not have the right to exist or describing it in racist terms is not only wrong but undermines the very principle we all have pledged to uphold," he added.

Iranian President Mahmoud Ahmadinejad has repeatedly denied the Holocaust and this month described Israel as a "cancerous tumour". In 2005 he caused uproar by being quoted as saying that Israel should be "wiped off the map".

Persian language scholars say a more correct translation of his comment would read: "Israel must vanish from the page of time."

Ban was attending the NAM summit despite calls from the United States and Israel that he should boycott the event.

(Reporting By Marcus George; Editing by Alistair Lyon)