US government plans requiring travellers crossing its borders to include pre-paid card balances when declaring their financial position, have been cast into doubt by some.

The plans, which were first muted by the US Treasury’s Financial Crimes Enforcement Network (FinCen) a year ago, are designed to combat money laundering and terrorist financing.

However, the plans have come in for criticism regarding the feasibility of validating what has been declared and enforcement issues. Assistant director of the Retail Payments Risk Forum at the Federal Reserve Bank of Atlanta, Cynthia Merrill said: "How can you tell how much money is loaded on the prepaid card to validate the declared value? In fact, how will enforcement officials even distinguish prepaid cards from credit and debit?"

A statement from the Department of Homeland Security outlined how the plans would be put into practice saying a "handheld reader with features that will, among other things, allow law enforcement to quickly and accurately differentiate between a traveller's debit, credit, and prepaid product...in a manner which imposes minimal to no inconvenience to individuals and complies with US laws, regulations, and procedures."