<a href="https://www.thenationalnews.com/tags/un/" target="_blank">UN</a> nuclear chiefs have been left disappointed after "no further progress" was made in explaining mysterious uranium traces in <a href="https://www.thenationalnews.com/tags/iran/" target="_blank">Iran</a>. The head of the International Atomic Energy Agency said hopes of a breakthrough after he <a href="https://www.thenationalnews.com/mena/iran/2023/03/03/iaea-chief-grossi-arrives-in-iran-for-high-level-meetings/" target="_blank">visited Tehran</a> in March have not materialised. Rafael Grossi said the IAEA could not "provide assurance that Iran's nuclear programme is exclusively peaceful" until it clears up the presence of uranium at undeclared locations. Iran, which denies pursuing an atomic bomb, has frustrated inspectors by removing IAEA monitoring equipment from nuclear sites. Mr Grossi's visit in March ended with a joint statement in which Iran said it was ready to "provide further information and access" in a "spirit of collaboration". But although there were small initial steps to restore surveillance, Mr Grossi told diplomats on Monday: "I regret that no further progress has been made." He told an IAEA board meeting that Iran "still needs to provide the agency with technically credible explanations" for the presence of uranium at two sites, Varamin and Turquzabad. A further dispute relates to a discrepancy in an inventory of nuclear material at a uranium conversion site. "These outstanding safeguards issues ... need to be resolved for the agency to be in a position to provide assurance that Iran’s nuclear programme is exclusively peaceful," Mr Grossi said. "I call upon Iran to work with the Agency in earnest and in a sustained way towards the fulfilment of the commitments contained in the joint statement." Mr Grossi later said at a press conference that the IAEA was "not accusing [Iran] of anything" but asking questions so that "everything is accounted for". "There are the traces, therefore there was nuclear material. Where is the nuclear material?," Mr Grossi asked. "We hope to come at some point to an agreement but at this point in time we are nowhere near this," he added. Iran has separately flouted its commitments under the 2015 nuclear deal with world powers, which the US abandoned under <a href="https://www.thenationalnews.com/tags/donald-trump/" target="_blank">Donald Trump's</a> presidency. Talks on reviving the pact have been in limbo for more than a year. Western powers say Iran has no credible civilian reason to enrich uranium to 60 per cent, well above the deal's 3.67 per cent limit.