By Jeremy Herb - 12/13/13 09:55 AM EST
Iran and the six world powers need more time to resolve the technical issues surrounding the six-month interim deal struck last month.
"After four days of lengthy and detailed talks, reflecting the complexity of the technical issues discussed, it became clear that further work is needed," said Michael Mann, a spokesman for EU foreign policy chief Catherine Ashton.
"There will now be consultations in capitals, in the expectation that technical talks will continue soon,” Mann said.
The deal reached between Iran and the six world powers — the United States, Britain, France, Germany, Russia and China — trades $7 billion in sanctions relief with a curbing of Iran’s nuclear activities.