Iranian Deputy Foreign Minister Abbas Araqchi said on Tuesday world powers had a "good" first reaction to Tehran's proposals for easing the stand-off over its nuclear programme and that details would be discussed in the afternoon.

The minister, speaking to reporters after Iran made a PowerPoint presentation at the start of a two-day meeting with the six powers in Geneva, said the atmosphere in the discussions had been "positive". He gave no details of the proposals, describing them as "confidential".

Western diplomats were not immediately available for comment. They had earlier called on Iran to put forward concrete proposals to allay their concerns about the Islamic state's nuclear energy programme, which the West fears may aimed at developing a nuclear weapons capability. Iran denies this.

The six powers - the United States, France, Britain, Russia, China and Germany - want Iran to curb sensitive nuclear uranium enrichment. Iran wants them to ease tough sanctions that have severely damaged its lifeblood oil exports.

"There is a positive atmosphere. Our plan was given and it's planned that in the afternoon we will discuss more details, but the first reactions were good," Araqchi told reporters after the morning session broke for lunch.

"It's a completely realistic, balanced and logical plan." Talks were due to resume around 3 p.m. (1300 GMT).

The Geneva talks, the first since relative moderate Hassan Rouhani was elected Iran's president in June on a platform to ease its international isolation, is seen as the best chance for years to defuse a festering stand-off over Iran's nuclear ambitions that has heightened the risk of a new Middle East war.