UN Secretary-General Ban Ki-moon has expressed the hope that the dispute over Iran's nuclear programme can be resolved through dialogue.
Asked whether he was concerned about Iran's nuclear programme, he told the Italian newspaper La Stampa: "Yes, I'm very worried about Iran's nuclear progress. I hope that, even with the change in negotiators, things can move forward; it is important to continue negotiating with Iran."
UN Secretary-General Ban Ki-moon
Last week, the Islamic state appointed a new negotiator widely seen as taking a tough line in international talks intended to head off further UN sanctions against Iran.
Mr Ban said he had met Iranian President Mahmoud Ahmadinejad briefly during the recent UN General Assembly, and was prepared to meet him privately.
"I have said with great urgency on many occasions that the differences can be resolved through peace, through dialogue; a war or military action is not desirable in any way," Mr Ban said.
The United States yesterday imposed new sanctions on Iran, partly over its nuclear programme, and has refused to rule out military action.
Political directors from the five permanent members of the UN Security Council are expected to meet in Europe next week to discuss imposing a third round of UN sanctions.
The West believes Iran is seeking to build an atomic bomb, but Iran says its nuclear programme is for peaceful purposes.