Officials in Kabul said the rough-hewn gold bars, commonly placed in hand luggage and jacket pockets, are fully declared and legal to fly, The New York Times reported Saturday.
Kabul gold dealers and former and current airport officials say there has been an increase in such gold shipment since early summer.
The governor of the Central Bank of Afghanistan, Noorullah Delawari, said, "We are investigating it, and if we find this is a way of laundering money, we will intervene."
Afghan and Western officials said money laundering occurs often.
"Right now, you're stuck in the situation we usually are: Is there something bad going on here or is this just the Afghan way of commerce?" a senior American official who watches illicit financial networks said.
The gold shipments are similar to the much larger problem of cash smuggling, the newspaper said.
Approximately $4.5 billion in cash was taken out through the airport in 2011, the central bank said.
Worries about money laundering continue, a report issued last week by the U.S. Special Inspector General for Afghanistan Reconstruction indicated.
The report also said the unblocked "bulk cash flows raise the risk of money laundering and bulk cash smuggling -- tools often used to finance terrorist, narcotics and other illicit operations."