The European Union said Friday that expert-level talks in Vienna on Tehran's nuclear program had been interrupted for further consultations, but were expected to resume soon.
"Reflecting the complexity of the technical issues discussed, it became clear that further work is needed," said Michael Mann, spokesman for the EU's foreign policy coordinator, Catherine Ashton.
There will "now be consultations in capitals, in the expectation that technical talks will continue soon," he added.
He did not say whether specific issues had created problems at the talks, which went on for four days at the headquarters of the UN's International Atomic Energy Agency (IAEA). They were attended by experts from Iran, Germany, the European Union, the United States, China, Britain, France, Russia, and the IAEA.
The talks focused on how to implement last month's landmark deal for Tehran to scale down its nuclear program in return for a limited easing of international sanctions.
The Geneva deal is scheduled to go into force early next year for a period of six months, during which a final agreement is meant to be forged requiring still further nuclear concessions from Tehran in exchange for a more permanent removal of sanctions.
In another apparent sign of a thaw in ties between Iran and the West since the deal, a European Parliament delegation has arrived in Tehran in the first visit by the EU's legislative body to Iran in more than six years.
Iran's official IRNA news agency said on Friday that the eight-member delegation would be in the country until Wednesday.
The delegation is to meet with Iranian politicians and officials, as well as with dissident filmmaker Jafar Panahi and human rights lawyer Nasrin Sotoudeh. In 2012,Panahi and Sotoudeh jointly won the prestigious Sakharov prize awarded by the European Parliament.
A visit by such a delegation had originally been planned for autumn of last year. It was called off after Iranian authorities refused to allow meetings with Panahi and Sotoudeh, who were both in prison at the time.
They have since been released, making official permission to meet with them unnecessary.
tj/pfd (dpa, AFP, AP, Reuters)