Iran is optimistic that the long-standing dispute over its nuclear programme will end Saturday, the Islamic state's Foreign Minister Mohammad Javad Zarif said as he arrived in Vienna.
"All nuclear sanctions will be lifted today," he told reporters.
Zarif was expected to meet with EU chief diplomat Federica Mogherini, US Secretary of State John Kerry and International Atomic Energy Agency (IAEA) Director General Yukiya Amano to mark the implementation of the broad nuclear agreement that Tehran closed with six world powers in July.
Iran and the group of the United States, Britain, France, Germany, Russia and China were waiting for a final report by the Vienna-based IAEA Saturday to confirm that Tehran has scaled down its nuclear programme.
This confirmation will oblige the EU and US to immediately lift sanctions including an embargo on Iranian oil, according the July 14 deal.
Iran had agreed in July that it would dismantle thousands of uranium enrichment centrifuges, reduce its stocks of enriched uranium from 12 tons to hundreds of kilograms and to pour concrete into its plutonium-producing Arak reactor.
The downsizing of Iran's civilian nuclear programme, along with intrusive IAEA inspections in the coming years, are meant to ensure that Iran cannot make nuclear weapons.
The implementation of the nuclear deal was set to come 13 years after revelations that Tehran had secretly built nuclear facilities and had dabbled in nuclear weapons research.