Wealthy American clients seeking to prevent the disclosure of their identities as part of a tax-evasion investigation by the US Justice Department sued UBS on Tuesday in a Swiss federal court.

The lawsuit accuses UBS and Switzerland's financial regulator, the Swiss Financial Market Supervisory Authority, or Finma, of violating Swiss bank secrecy laws and of conducting what Swiss law considers illegal activities with foreign authorities. It also named Peter Kurer, the chairman of UBS, and Eugen Haltiner, the chairman of Finma, as defendants.