Geneva: Iran and six world powers are making progress in talks aimed at ending a decade-long nuclear stand-off between Tehran and the West, but the discussions are “tough”, Iran’s foreign minister said on Thursday.

Mohammad Javad Zarif made the comment after a first session in the two-day negotiations in Geneva, which are seeking to build on a diplomatic opening after the June election of Hassan Rouhani, a relative moderate, as Iran’s new president.

The powers hope to reach a “first step” deal to ease concern over Tehran’s nuclear programme though both sides say a breakthrough is far from certain.

“What we’re looking for is a first phase, a first step, an initial understanding that stops Iran’s nuclear programme from moving forward and rolls it back for the first time in decades,” a senior US official said.

“The talks went well,” Zarif said after the morning session between Iran, the United States, Britain, France, Germany, Russia and China. “I’m hopeful that we can move forward. We are making progress, but it’s tough,” he said.

Iran’s Deputy Foreign Minister Abbas Araqchi said he hoped a deal could be struck but that the sides remained far apart.

A spokesman for European Union foreign policy chief Catherine Ashton, who is coordinating talks, described the morning session as “good”.

“The talks are extremely complex and they are now getting into a serious phase. We very much hope there will be concrete progress here in the next couple of days,” Michael Mann said.