A top official with the United Nations nuclear agency is reporting progress in two days of talks with Iranian officials.

International Atomic Energy Agency Deputy Director Olli Heinonen said the talks that concluded Thursday in Tehran were constructive and progress was made.

Iranian deputy nuclear negotiator Javad Vaidi said the two sides had "serious and good meetings."

Wednesday, Iranian President Mahmoud Ahmadinejad remained defiant in the nuclear standoff. He said the United Nations should not expect Tehran to suspend its uranium enrichment activities, as demanded by the international community.

The U.N. Security Council has imposed two sets of sanctions on Iran because of its refusal to suspend uranium enrichment.

On Monday, the U.N. nuclear agency said inspectors have seen a "marked slowdown" in Iran's nuclear enrichment program.

The United States and its Western allies accuse Iran of trying to develop nuclear weapons. Iran says its nuclear program is for peaceful purposes.

Enriched uranium can be used to produce nuclear weapons, or as fuel to generate energy.

Some information for this report was provided by AFP, AP and Reuters.