Negotiators at talks to revive Iran's nuclear deal were cautiously optimistic that the parties were moving toward an agreement, with the head of the UN's atomic energy agency set to travel to Tehran this weekend.
"We are at the final stages of the ViennaTalks on the JCPOA. Some relevant issues are still open and success is never guaranteed in such a complex negotiation. Doing our best in the coordinator's team. But we are definitely not there yet," Enrique Mora, the European Union's coordinator for the talks, said on March 3.
Numerous rounds of talks involving U.S. and Iranian negotiators have been held in the Austrian capital over the past year to reach a new agreement to replace a 2015 deal exchanging curbs on Iranian nuclear activities for sanctions relief.
Then-U.S. President Donald Trump pulled Washington out of that deal in 2018 and reinstated crippling sanctions against Iran, and Tehran subsequently fell out of compliance with some terms of the agreement.
Progress has been reported, but Tehran wants the issue of uranium traces found at old but undeclared sites to be dropped and closed permanently, Reuters quoted an anonymous Iranian official as saying.
German Chancellor Olaf Scholz on March 2 urged Iran to move quickly to resolve any remaining issues and said a decision "must not be postponed any longer and cannot be postponed any longer."
Russian envoy Mikhail Ulyanov, who has been widely regarded as the most publicly optimistic among the delegation leaders on the prospect of a new deal, said he thought enough progress had been made to believe the talks wouldn't collapse.
"There are some issues that need to be finalized.... The outstanding issues are relatively small but not yet settled," he said.
Adding a sense of urgency to the atmosphere was a quarterly report from the International Atomic Energy Agency (IAEA) stating that Iran has sharply increased its stockpile of enriched uranium.
The report, according to several international news agencies, said Tehran now has more than 33.2 kilograms of highly enriched uranium with a purity of up to 60 percent, a level which means it can quickly be processed to create weapons-grade material.
It takes around 25 kilograms of weapons-grade uranium, which is around 90 percent purity, to make an atomic bomb.
With headway being made, IAEA Director-General Rafael Mariano Grossi set plans to travel to Tehran for meetings with senior Iranian officials on March 5, the IAEA said in a statement.
The plans for a visit were first reported by an Iranian news agency affiliated with that country's top security body.
Iran acknowledged the advances in some areas but warned "extra efforts" were still needed to revive the deal.
"#ViennaTalks still continue. Premature good news does not substitute good agreement," the Iranian Foreign Ministry spokesperson Saeed Khatibzadeh said on Twitter.
The IAEA said Grossi would address journalists after returning from Iran to Vienna late on March 5.