Meetings held in Vienna between Iran and the P5-plus-1 -- the United States, China, Russia, Britain, France and Germany -- resulted in more planned meetings March 17-20, again in Vienna, said European Union Foreign Policy Chief Catherine Ashton.
Experts from the countries are scheduled to meet in early March, the Wall Street Journal reported.
"We have had three very productive days during which we have identified all of the issues we need to address in reaching a comprehensive and final agreement," Ashton said. "There is a lot to do. It won't be easy but we have made a good start."
A senior U.S. official whose name wasn't reported said this week's talks were "very workmanlike ... it was engaged."
"It covered all of the issues that need to be put on the table," the official added.
The two sides must reach an agreement by a July deadline and plan to meet monthly for the next four months, the Journal said.
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