United Nations Secretary General Ban Ki-moon said Holocaust denial is intolerable, while attending a ceremony marking the upcoming International Holocaust Memorial Day in New York.

The ceremony, at Park East Synagogue in New York, was attended by representatives from countries including Germany, India, Poland, South Korea, Hungary and Italy.

Rabbi Arthur Schneier, who presided over the ceremony, called Ban a "mensch", AFP reported on Saturday. Despite his recent criticism of Israel's settlement building, the rabbi said Ban believes in "compassionate diplomacy, diplomacy from the heart."

"We can never tolerate anybody who denies the Holocaust," the UN chief said, calling the Holocaust the "darkest chapter in history." He praised Holocaust survivors, saying they serve as a symbol of hope and bravery.

Israel's UN ambassador and the Consul General of Israel in New York also attended the ceremony.

UN Ambassador Meron Reuben lauded the ceremony, saying that when the UN designated the International Holocaust Memorial Day five years ago, no one believed that it would receive this much world wide recognition.

The official International Memorial Day is commemorated worldwide on January 27.