UNITED NATIONS - UN Secretary-General Ban Ki- moon on Tuesday left New York for Tehran, the capital of Iran, to attend the 16th Non-Aligned Movement (NAM) summit, UN spokesman Farhan Haq said at a daily news briefing here.

Ban will convey to Iran "the clear concerns and expectations of the international community on the issues for which cooperation and progress are urgent for regional stability and the welfare of the Iranian people. These include Iran's nuclear program, terrorism, human rights and the crisis in Syria," the spokesman said.

"The secretary-general looks forward to the summit as an opportunity to work with the participating heads of state and government, including the host country, towards solutions on issues that are central to the global agenda, including follow-up to the Rio+20 Conference on Sustainable Development, disarmament, conflict prevention, and support for countries in transition."

Ban also takes seriously his responsibility and that of the United Nations to pursue diplomatic engagement with all of its member states in the interest of peacefully addressing vital matters of peace and security, Haq said.

Last Wednesday, the UN chief announced his decision to attend the NAM summit, slated for August 30-31 in Tehran, despite strong opposition from the United States and its close ally Israel, who had even termed Ban's possible trip to Tehran as a "big mistake."

Nearly 100 members of the NAM have indicated their willingness to take part in the upcoming summit, reports said.

The United States and its Western allies have long accused Iran of secretly developing nuclear weapons, but Tehran insists that its nuclear program is for civilian purposes only. ?

The five permanent members of the UN Security Council, Britain, China, France, Russia and the United States, plus Germany have held many rounds of negotiations with Iran on the issue, with no substantial progress achieved so far.

Ban wants to see an Iranian role in the political settlement to the 17-month Syrian crisis, but his intention was blocked by Washington and its allies.

"The secretary-general will have a range of meetings with Iranian officials, and is expected to meet the (Iranian) supreme leader and the president," Haq said.

The secretary-general is scheduled to return to New York on Saturday, he added.