"Mr. Tero Varjoranta stepped down starting from May 11, 2018," the spokesperson of IAEA was quoted as saying by the Helsingin Sanomat newspaper.
The media outlet noted that Varjoranta's resignation comes just days after the decision of the United States to withdraw from the Iran nuclear deal.
"The Director General appointed Massimo Aparo Acting Deputy Director General and Head of the Department of Safeguards on 11 May 2018. Prior to this, Mr Aparo was Acting Director, Office for Verification in Iran, since 1 March 2016," the press service of the agency said in its website.
US President Donald Trump earlier this week announced that the United States would withdraw from the Joint Comprehensive Plan of Action (JCPOA). The president also vowed to re-impose the highest level of economic sanctions against Iran in response to Tehran's development of its nuclear program.