US Secretary of State John Kerry and Iranian Foreign Minister Mohammad Javad Zarif began a bilateral meeting on Iran's nuclear program.
The head of the Atomic Energy Organization of Iran (AEOI), Ali Akbar Salehi, and the adviser and brother of the Iranian President, Hossein Fereydoun Rouhani, also arrived in the Austrian capital.
Salehi's presence "despite health problems, indicates the seriousness with which Iran attends the negotiations," RIA Novosti cited Zarif as saying.
