The United Nations' nuclear watchdog says Iran has taken "a step in the right direction" with regard to questions on its nuclear program, but warns that the issues have not been "completely addressed."
The acting head of the International Atomic Energy Agency (IAEA), Cornel Feruta, said there had in the past few weeks been "engagement" from Iran on questions relating to its nuclear safeguards declarations to the agency.
The IAEA told Tehran last month that "time is of the essence" in addressing what it described as concerns about the completeness of Iran's safeguards declarations to the agency.
The IAEA has not specified what its concerns relate to, but diplomats said the agency had been waiting for information from Tehran regarding samples taken earlier this year from a warehouse near the capital, Tehran.
Uranium particles were found in the environmental samples from the site, which Israeli Prime Minister Benjamin Netanyahu accused Iran of using for undeclared nuclear activity.
Iran has denied that, saying the site was a carpet-cleaning facility.
Feruta told journalists in Vienna that the progress was the result of meetings with various senior Iranian officials in recent weeks.
"This is an ongoing process.... I cannot prejudge how this is going to end. The engagement doesn't mean that the issues are completely addressed, but it's a step in the right direction," Feruta said.
Feruta added that the questions from the IAEA did not touch directly on the 2015 nuclear deal between Iran and world powers.