Nuclear talks between Iran and world powers are set to resume in Geneva on activating a landmark deal to curb Tehran's nuclear programme.
A two-day meeting that starts on Thursday between Abbas Araqchi, Iran's negotiator, and Helga Schmid, representative of the P5+1 group of world powers, has been endorsed by Iran's foreign minister with optimism.
"The nuclear talks are continuing with seriousness and a strong political will," Javad Zarif said on his Facebook page, adding that hours of technical talks with experts from the P5+1 group in December had produced "positive results".
Iranian foreign ministry spokeswoman Marzieh Afkham said the talks will focus on remaining issues "pending a political decision" before the deal can go into effect on January 20, a date mooted by both sides.
The US State Department confirmed on Wednesday that US Under Secretary of State for Political Affairs Wendy Sherman was also travelling to Geneva to attend the talks.
Technical experts from Iran and the EU-chaired P5+1, comprising the US, China, Russia, Britain, France and Germany, held two sessions in Geneva in mid and late December as they seek to fine-tune a deal reached on November 24.
Under the deal, Iran is to curb parts of its nuclear drive for six months in exchange for modest relief from international sanctions and a promise by Western powers not to impose new measures against the Iranian economy, which has been battered by the embargo.
In early December, experts also held four days of talks in Vienna, but the Iranians walked out after Washington expanded its sanctions blacklist against Tehran.
The interim deal is meant to buy time for diplomacy to clinch a lasting agreement that would allay Western suspicions that Iran is covertly pursuing a nuclear weapons capability.
Tehran denies wanting nuclear weapons, but many in the international community suspect otherwise.