UN Secretary General Ban Ki-moon has said he is worried about Iran's nuclear programme but hopes a stand-off with the international community can be resolved through dialogue.
Last week Iran appointed a new negotiator widely seen as taking a tough line in international talks intended to head off an intensification of existing UN sanctions against Iran.
Saeed Jalili, Iran's deputy foreign minister for European and American affairs, was named new chief nuclear negotiator after Ali Larijani resigned.
Mr Ban said he hoped that things could move forward even with the change in negotiators.
He said it is important to continue negotiating with 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 if necessary.
'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 West believes Iran is seeking to build an atomic bomb while Iran says its nuclear programme is for peaceful purposes.
The US 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 - the US, Russia, China, France and Britain - and Germany are expected to meet in Europe next week to discuss imposing a third round of UN sanctions.
