The boss of US regulator FinCEN has outlined what Bitcoin exchanges need to do to keep the feds happy and stay out of prison.

Jennifer Shasky Calvery, director of the Financial Crimes Enforcement Network, told the American Banker that the US had no ideological beef with alternative currencies, but expects them to follow existing anti-money laundering rules.

Calvery said: "Digital currencies are just a financial service and those who deal in them are a financial institution. Any financial institution and any financial service could potentially pose an AML[anti-money laundering] threat."

She said action against Liberty Reserve was simply one criminal case against one suspected law breaker and had no bearing on the industry as a whole.

Asked if FinCEN considered putting its recent guidance out for comment Calvery said they did not because it is just an interpretation of existing rules.

She said she welcomed innovation in financial services but those involved needed to act with transparency and integrity.

Calvery said: "I think innovation in financial services industry holds out great promise on so many levels for commerce and for social reasons like providing services to the unbanked. But like any financial services, it comes with an obligation and those obligations to protect the U.S. financial system from money laundering need to be taken seriously."

Apparently without irony Calvery said: "I actually heard the CEO of a bank say recently that there is a reason that financial institutions have to obtain licenses and to register. And that's because it is a great bestowal of trust to the bankers, to the financial service providers, to be able to be part of the U.S. financial system, to be able to be part of the global financial system. And that trust and that privilege come with obligations."

Calvery joined FinCEN last September from the Department of Justice.

The full interview is available from American Banker here.