Iran said Saturday it is prepared if necessary to release footage of an incident with a UN nuclear inspector last week that led to it cancelling her accreditation.
US Secretary of State Mike Pompeo accused Iran of "an outrageous and unwarranted act of intimidation," while the European Union voiced "deep concern".
Iran's Atomic Energy Organisation spokesman Behrouz Kamalvandi said that a check at the entrance gate to the Natanz uranium enrichment plant "triggered the alarm multiple times, showing (the inspector) was either contaminated with certain materials or had them on her".
He did not specify what the materials were or whether they had actually been found in her possession, AFP reported.
"We've announced that if needed we will even present the footage of this," Kamalvandi told a news conference, noting that Iran's "bitter experiences" of nuclear sabotage had led to the strict system of checks.
Meanwhile, the IAEA said Thursday that the inspector was briefly prevented from leaving the country, adding that her treatment was "not acceptable."
However, Iran's ambassador to the agency, Kazem Gharib Abadi, denied the inspector was ever detained, saying she was allowed to leave even though an investigation was still ongoing.
According to AFP, under a 2015 deal between Iran and major powers that has been undermined by Washington's withdrawal last year, its nuclear facilities are subject to continuous monitoring by the IAEA.