The Justice Department revealed a total of eight lenders are being looked at on suspicion of facilitating such criminal activity by US citizens.
Disclosure of the probes has been revealed on the group's website in a section that outlines the Tax Division's Offshore Compliance Initiative and the body said the action has dealt "fabled Swiss bank secrecy a devastating blow".
UBS AG has previously been charged with helping US clients evade tax and the new push could see other institutes following suit.
The department - the attorney general at which is currently Eric Holder - added: "Grand jury investigations have been opened into eight additional offshore banks across the world. The outcome cannot be measured in litigation results alone."
However, none of the lenders embroiled in the probes have yet been named.
By Gary Cooper