UN atomic watchdog chief Yukiya Amano welcomed Iran's compliance with measures to lift suspicions about its nuclear programme on Monday, but cautioned that all doubt had not been cleared.
In a report last month, Amano revealed that Iran had so far stuck by its agreements with the IAEA and implemented all recently agreed measures -- as talks continue with western powers in a bid to strike a major deal by July.
Tehran even addressed matters related to bomb-making, including the use of detonators, for the first time in six years -- an issue that has long been of concern to the international community, although Iran insists the aims of its programme are purely peaceful.
"Iran has engaged with the agency substantively, including in the clarification of issues related to the use of exploding bridge wire detonators," Amano told IAEA member states Monday.
Tehran's further agreement in May to implement five new practical measures "is a further welcome step forward," he added.
As on previous occasions however, Amano highlighted that the IAEA was "not in a position to provide credible assurance about the absence of undeclared nuclear material and activities in Iran, and therefore to conclude that all nuclear material in Iran is in peaceful activities."
Iran and western powers are striving to draft a potentially historic nuclear deal by July 20.
A next round of talks -- held separately from Iran's meetings with the IAEA -- was planned for June 16-20 in Vienna.
The last round in mid-May ended with no apparent progress on a deal.