Officials from Iran and six world powers are set to start another round of discussions on implementing a deal aimed at easing concerns over Iran's nuclear program.
The technical talks between experts in Geneva will focus on implementing the November deal to scale back parts of Iran's nuclear program in exchange for easing some international sanctions.
On the eve of the talks, Iran's top negotiator, Foreign Minister Javad Zarif, expressed optimism the two sides could resolve all issues to implement the deal.
However, Reuters quoted unnamed diplomats as saying talks could face fresh hurdles.
The agency quoted diplomats as saying Iranian plans to press ahead with the development of more advance centrifuges is causing concern in the West.
Nuclear experts from Iran and the six powers -- the United States, France, Britain, Germany, Russia, and China -- have already held several rounds of talks.
Based on reporting by AFP and Reuters