"The meetings were useful, raised mutual insight into our differing positions," Iranian negotiator Hamid Baeedinejad told the official IRNA news agency at the end of the three-day talks in Vienna. "Everyone came well-prepared ... addressing issues in minute technical details can facilitate hard political decisions."
He said the results would be submitted on Monday to Iranian Foreign Minister Mohammad Javad Zarif and European Union foreign policy chief Catherine Ashton Who acts on behalf of the six world powers - the United States, France, Germany, Russia, China and Britain.
Ashton and Zarif are to hold their third round of high-level nuclear talks on April 8-9 in the Austrian capital, part of efforts to reach a comprehensive agreement by late July. It seeks to limit Iran's controversial uranium enrichment activities in return for a lifting of economic sanctions.
Top Iranian nuclear negotiator, Abbas Araghchi, was quoted as saying by IRNA that "all technical issues needing deeper experts' studies, including the heavy-water Arak reactor, are being addressed at the latest round of talks.
"Talks will continue on enrichment and other (sensitive) issues until final settlement," he added.
Western officials say however wide differences remain between the two sides.