Secretary of State Mike Pompeo signed off on the waiver extensions on Monday, Reuters reported.
Current and former officials familiar with the matter said Pompeo had opposed extending the waivers, which are among the few remaining components of the 2015 nuclear deal between Tehran and world powers that the administration had not canceled.
However, the officials told AP that Treasury Secretary Steven Mnuchin had prevailed in an internal debate on the subject last week.
Mnuchin reportedly argued that the coronavirus pandemic made eliminating the waivers unpalatable at a time when the administration was being criticized for refusing to ease sanctions to deal with the outbreak, which has hit Iran hard. The officials were not authorized to publicly discuss the decision and spoke to AP on condition of anonymity.
The move by the Trump administration, which in 2018 withdrew from the 2015 Iran nuclear deal and reimposed sanctions on Iran, will allow non-proliferation work to continue at the Arak heavy-water research reactor, the Bushehr nuclear power plant, the Tehran Research Reactor and other nuclear facilities.