(Reuters) U.S. authorities are moving toward taking legal action against Wegelin & Co, which could lead to an indictment of one of Switzerland's last pure private banks, on charges that it enabled wealthy Americans to evade taxes, according to two persons with knowledge of the case.

The latest turn in the Wegelin case comes amid a broad criminal probe by the U.S. Justice Department of 11 Swiss and Swiss-style banks, including Wegelin, suspected of selling offshore tax evasion services to tens of thousands of wealthy Americans. Inquiries, growing out of scrutiny of UBS, are focused on Credit Suisse AG and Basler Kantonalbank among others.

Wegelin confirmed on Wednesday that three of its employees had been indicted by U.S. prosecutors in Manhattan for selling tax evasion services to wealthy Americans.

Wegelin is a small bank where eight partners hold unlimited liability for its operations. It has no U.S. offices or branches and it conducted its tax evasion business in part through correspondent banking accounts at UBS in Stamford, Conn.