A senior United Nations official says talks between the U.N. nuclear watchdog and Iran about Tehran's nuclear program failed to reach an agreement and no date has been set for more meetings.
The International Atomic Energy Agency's top nuclear inspector, Herman Nackaerts, said Wednesday he and his team had intensive discussions but "could not finalize the structured approach under negotiation for a year and a half."
The talks in Vienna were the 10th held by the U.N. nuclear agency since the beginning of last year with Iranian officials, as its investigators continue to seek access to Iran's nuclear facilities and documents.
The IAEA is concerned about Iran's potential development of nuclear weapons, and wants to visit facilities such as the Parchin military site to resolve questions about the program.
Iran insists Parchin is a standard military facility and that its nuclear program has only peaceful purposes.
Meanwhile, in Istanbul, Iran's top nuclear negotiator, Saeed Jalili, is also holding talks with European Union policy chief Catherine Ashton.
Their meeting follows a failed round of negotiations in early April with a group of world powers that includes the five permanent members of the U.N. Security Council, plus Germany.
Those nations are pushing for Iran to stop some of its uranium enrichment activity, while Iran has demanded they recognize its right to enrich uranium.
The U.N. Security Council has passed multiple rounds of sanctions against Iran related to its nuclear program. The United States and other Western nations have enacted their own sanctions, included targeting Iran's key oil exports.
Analysts and diplomats say any movement in the decade-old standoff will probably have to wait until after Iranians vote on June 14 for a successor to President Mahmoud Ahmadinejad.
Also Wednesday, the United States blacklisted an exchange house and a trading company based in the United Arab Emirates, saying they had dealt with Iranian banks that Washington has declared off limits.
The U.S. Treasury Department said al-Hilal Exchange and al-Fida International General Trading had provided financial services to Iran's blacklisted Bank Mellat.
The move bars U.S. individuals and companies from dealing with the two UAE-based firms, effectively cutting them off from the U.S. financial system.