US prosecutors late on Tuesday charged three Swiss bankers with conspiring to help US citizens evade over $1.2bn in assets from the IRS.

The filed indictment, which refers to ‘Swiss Bank A' only, shows that Roger Keller, Urs Frei and Michael Berlika plotted to open and service several secret accounts for US clients as they tried to escape from banks including UBS after the lenders began to be investigated by the IRS in 2008 and 2009.

The Department of Justice said fake accounts were set up in jurisdictions including Hong Kong, Panama and Liechtenstein.

The indictment comes in the midst of Swiss -US talks that attempt to resolve a US probe of offshore tax dodging.