Olli Heinonen, deputy director of the U.N. International Atomic Energy Agency (IAEA), speaks with Javad Vaeedi (L), Iran's deputy nuclear negotiator in Tehran October 29, 2007. (Xinhua/Reuters Photo)
"We have done many things so far but there remains a lot of other work that hopefully will be resolved," Heinonen was quoted by Iran's state media as saying upon his arrival at the airport on Monday.
The talks were crucial since the result of them could be basis for a report over the status of the Iranian uranium enrichment program by the IAEA chief Mohamed ElBaradei by the end of November.
The United States and some other Western countries fear Iran may try to develop atomic bombs under a civilian cover, however Tehran insists its nuclear program is for peaceful purposes only.
The UN Security Council has already issued two sanction resolutions against Iran's nuclear program since last December, but both of them failed to persuade the Islamic Republic to give up uranium enrichment work.
Washington now is trying to push the UN Security Council to adopt a third resolution against Tehran's defiance, but Iran's cooperation with the IAEA and the EU in the past months has let other world powers agree to wait ElBaradei's report until November to make their decision.
(Xinhua News Agency November 2, 2007)