Four bankers with Switzerland-based Credit Suisse Group are accused of helping U.S. taxpayers hide as much as $3 billion in assets from the IRS.

The conspiracy indictment was handed down Wednesday in U.S. District Court in Alexandria, Va. Arrest warrants have been issued for all four who are believed to be in Switzerland: Marco Parenti Adami, Emanuel Agostoni, Michele Bergantino and Roger Schaerer.

The indictment itself does not specify the bank as Credit Suisse, but a law-enforcement official with knowledge of the case confirmed the bank's identity to The Associated Press but insisted on anonymity because he was not authorized to speak publicly on the case.

The Obama administration has been cracking down on foreign banks that it believes were serving as tax havens.