The gold was delivered to the central bank Tuesday night. After purchasing the gold, Iran had to deposit it in South Africa as sanctions blocked its way to Iran, semi-official Fars news agency quoted Central Governor Valiollah Seif as saying.
The report did not mention where nor when did Iran purchase the gold.
Seif thanked Iranian nuclear negotiators for the return of the gold, saying that their efforts at the Vienna talks helped free the frozen asset.
Iran has received 4.2 billion U.S. dollars in unfrozen assets under the 2013 interim agreement with the United States and was then given another 2.8 billion dollars by the Obama administration last year in a bid to keep Tehran committed to the talks.