Iran and six world powers entered a crucial third day of talks Friday in Geneva, where they will try to close gaps on a proposed interim deal that would curb Tehran's nuclear program in exchange for sanctions relief.
Diplomats from both sides reported some progress following Thursday's session, but said substantial disagreements remain. The key sticking point appears to be to what extent Iran will be allowed to enrich uranium, participants said. Another is how much the sanctions will be relaxed.
Iranian Foreign Minister Mohammad Javad Zarif and Catherine Ashton, the European Union's top diplomat, have met repeatedly since Wednesday to work out differences. The two reportedly met briefly on Friday.
Iran's official IRNA news agency, quoting Iranian Deputy Foreign Minister Abbas Araghchi in Geneva, repeated Iran's insistence that it retain the right to enrich uranium, a process that yields materials both for bombs and civil nuclear power generation.
Tehran denies it wants to build a nuclear weapon. It has offered to suspend parts of its nuclear program and agreed to tighter inspections if the West relaxes sanctions that have devastated its economy.
Under discussion is a first-phase agreement meant to build trust while the two sides work out a more comprehensive deal that would ease Western concerns about Iran's ability to build nuclear weapons.
IRNA on Friday called the talks "complicated and tough."
So far, the U.S. has said it is prepared to offer what it calls limited and reversible sanctions relief, including unfreezing billions of dollars in Iranian funds overseas. Iran has said it would also like restrictions eased on its oil exports and banking sector.
U.S. lawmakers, meanwhile, are threatening to increase the sanctions. U.S. Senate Majority leader Harry Reid said Thursday he is committed to moving forward with a bill to impose new measures on Iran, in December, if negotiations are not successful.
Reid said the bill would "broaden the scope of current petroleum sanctions, place limitations on trade with strategic sectors of the Iranian economy that support its nuclear ambitions, as well as pursue those who divert goods to Iran."
President Barack Obama and Secretary of State John Kerry have been asking key Congressional leaders to hold off on any new sanctions against Tehran while the Geneva talks continue.
This is the third round of negotiations between Iran and the group known as the P5+1, which consists of United States, Britain, China, France, Russia and Germany.
The latest talks began Wednesday, building on a prior round of negotiations that ended two weeks ago. Analysts say those talks failed in large part because of objections by France.