Ashton Says Iran Nuclear Talks 'Substantive,' Announces Next Round

European Union foreign policy chief Catherine Ashton (left) and Iranian Foreign Minister Mohammad Javad Zarif in Vienna on March 18.

European Union foreign policy chief Catherine Ashton says Iran and world powers have held "substantive" and "useful" discussions at the second round of talks on a long-term settlement of the dispute over Iran's nuclear program.

Ashton said the sides would meet again in Vienna on April 7-9.

Ashton said the talks, which concluded on March 19 in the Austrian capital, dealt with Iran's uranium-enrichment activities, the future of Iran's heavy-water facility at Arak -- regarded as a possible source of plutonium -- and sanctions against the Islamic republic.

Iranian Foreign Minister Mohammed Javad Zarif appeared alongside Ashton and repeated her remarks in Persian.

In January, a six-month interim deal between Iran and the six powers -- Britain, China, France, Germany, Russia, and the United States -- went into force.