The bank – formally known as the Institute for Works of Religion or IOR – has suffered the ignominy of having one of its accounts closed by JP Morgan after stone-walling requests for information.
The sanction came less than two weeks after the US State Department listed the Vatican as being potentially vulnerable to money laundering.
A Milan affiliate of JP Morgan said it will shut the account by the end of the month after revealing Vatican bankers had been "unable to respond" to requests for details about payments into the account.
A spokesman for JP Morgan in Milan declined to comment, citing client confidentiality.
The Milan branch had been seeking information since 2010, when the Vatican bank was accused by authorities in Rome of contravening money-laundering regulations.