Since currency trading was liberalized, the BSP said dollars and other currencies could move freely in and out of the market without physically passing through the BSP.
Banks are required to monitor and report irregular dollar movements only under specific circumstances defined under the Anti Money Laundering Law.
According to BSP legal counsel and Assistant Governor Juan de Zuñiga, the BSP was not specifically privy to the case involving around $15,000 worth of fake dollar bills that went through banks and reached Hong Kong undetected.
But Zuñiga said bank officials should conduct their own internal investigation to determine if the counterfeit dollars, known as "super notes," did not slip by their internal checks due to conspiracy or any involvement by bank employees.
Zuñiga said the bank did not necessarily face any legal liabilities for attempting to pass off the currency as real when they were remitted or deposited elsewhere outside the country.
"They can argue good faith, especially if they are not habitually passing of fake currency for the real thing," he said. "But the bank would run after their clients themselves because naturally, they had to take the hit when the currency was caught by the entity they passed it to."
The Anti Fraud and Commercial Crimes Division of the Philippine National Police (PNP) reported that "super notes" are extraordinary counterfeit almost indistinguishable from genuine currency.
US authorities said that although local counterfeiters did not have the capability to produce high-quality counterfeits, these so-called "super notes" usually find their way into the financial system.
In the case reported by the PNP, two local banks sent off dollars to Hong Kong and the fake ones were not caught until they were checked by Hong Kong authorities.
Zuñiga said the BSP itself played no role in the physical inspection of dollar bills as they leave the country since the trading of foreign exchange has already been liberalized.
"The first line of defense really are dollar users themselves and then the banks," he said.
According to the BSP cash department, banks that are left in possession of fake currency would have to shoulder the financial liability if they were not able to detect the counterfeit early on.
"Since they are the ones hit, they would naturally want to run after their client or whoever slipped them the fake currency," said BSP cash department official Gratia Malic.