Cash outflows of as much as more than $3 billion has been reported out of Kabul in the past three years, raising fears among US investigators that it could be ill-gotten gains of the top Afghan officials being stashed away to financial safe havens abroad.
The cash packed into suitcases, piled into pallets, loaded into airplanes is declared and legal to move, but Wall Street Journal quoting US and Afghan officials say it appears to be money siphoned off from US and Western aid projects.
"Profits reaped from the opium trade are also a part of the money flow, as is cash earned by the Taliban from drugs and extortion," officials said.
Most of the funds passing through Kabul airport are moved by hawalas, the paper said, a mode often used in middle east and Asian sub-continent to make clandestine and secretive money transfers.
The currencies being used range from US Dollars, Saudi Rials, Pakistani Rupees and Norwegian Kroners to out of circulation Deutschmarks later traded for Euros.
Reports of alarming huge cash outflow come even as another US daily reported that top officials in the government of President Hamid Karzai have often blocked corruption investigations against well connected Afghans.
Washington Post quoting officials said Afghan prosecutors and investigators are routinely being told to cross names off the criminal files.
But US and Afghan officials say they are now targeting the flows in major anti-corruption and drug trafficking investigations because their size is more than Afghan government collects in tax and customs revenue annually.
"A lot of this looks like our tax payers money. And opium of course."
"You get boxes loaded on the back of airplanes. You get guys literally bringing boxes of cash on to the plane," Wall Street Journal quoted US officials as saying.