An official from Seoul told the Platts news service, on condition of anonymity, that refiners were making arrangements with the National Iranian Oil Co. to secure shipments of Iranian crude oil.
"We expect the agreement to come late this month or early next month," the official said.
The same official declined to provide details of the volume of crude oil expected from Iran.
U.S. Secretary of State Hillary Clinton in June included South Korea in a list of countries she said reduced the amount of crude oil purchased from Iran.
That meant that U.S. sanctions targeting the Iranian energy sector "will not apply to their financial institutions for a potentially renewable period of 180 days," she said in a statement.
The South Korean official said refiners needed to secure oil supplies "but will abide by U.S. and EU sanctions."
South Korea in June imported 24 percent less crude oil from Iran than it did during the same month last year. Seoul said it expects to receive deliveries from Iran in late September.
South Korea is the No. 5 oil importer in the world.