UN Secretary-General Ban Ki-moon will attend a summit meeting of leaders of non-aligned developing nations in Iran next week, defying calls from the United States and Israel to boycott the event, a UN spokesman said on Wednesday, Aug 22.

According to Reuters, UN spokesman Martin Nesirky told reporters that Ban will be in Tehran August 29-31 for a meeting of some 120 non-aligned nations, and for bilateral talks with senior Iranian officials.

"With respect to the Islamic Republic of Iran, the Secretary-General will use the opportunity to convey the clear concerns and expectations of the international community," he said. "These include Iran's nuclear program, terrorism, human rights and the crisis in Syria."

Ban is "fully aware of the sensitivities" linked to his visit, but he is also aware of his responsibilities as head of the United Nations, Nesirky said.

He noted that non-aligned nations comprise two-thirds of all UN member states.

One of Ban's responsibilities is "to pursue diplomatic engagement with all ... (UN) member states in the interest of peacefully addressing vital matters of peace and security," Nesirky said.

A UN Security Council diplomat said privately that it was important for the secretary-general to go. He said Ban should not turn his back on the entire non-aligned movement because one member, Iran, “happens to have a president who doubts the Holocaust and questions Israel's right to exist.”