* BCV, BCGE, Zuger, Graubuendner, Luzerner, St. Galler KB to join
* St. Galler says negotiations may end in late 2014
* Deadline to take up U.S. offer is Dec 31
* About 100 Swiss banks expected to participate
ZURICH, Dec 16 (Reuters) - Several Swiss regional banks said on Monday they would cooperate with U.S. officials to avoid prosecution in a crackdown on Swiss lenders suspected of helping wealthy Americans evade taxes through offshore accounts.
Banque Cantonale Vaudoise (BCV), Banque Cantonale de Geneve (BCGE), St. Galler Kantonalbank, Zuger Kantonalbank, Luzerner Kantonalbank and Graubuendner Kantonalbank said they were participating in the programme.
BCV's subsidiary Piguet Galland & Cie SA and St. Galler KB's subsidiaries Hyposwiss Privatbank Zurich AG and Hyposwiss Private Bank Geneve SA also decided to join the deal.
About a dozen banks have now come forward to say they are participating in the scheme brokered by the Swiss and U.S. governments this summer to allow banks to make amends for aiding tax evasion by paying fines and disclosing information.
All the cantonal banks that said on Monday that they would join the scheme said they had never focused on acquiring U.S. clients but said they could not completely rule out some customers had not met their U.S. tax obligations.
St. Galler KB said it would deliver data about its U.S. business that would not include client data to U.S. authorities by the end of June 2014. Based on this information, the U.S. Department of Justice would enter into individual negotiations with the bank that should end "at the earliest in late 2014".
The bank said it could not communicate on the expected amount of fines and corresponding provisions, but intended at this stage to leave its dividend unchanged.
BCGE said it estimated its 2013 profits should remain at a level equivalent to 2012. It had warned in September costs related to the U.S. programme could impact its profitability.
The cantonal banks said they would join the programme in a category for banks that admit or at least cannot rule out that some U.S. clients had untaxed money in their accounts.
About 100 banks are expected to take part in the scheme by the end of the year. They will have to face penalties of up to 50 percent of untaxed assets they managed for U.S. clients.
The U.S. Department of Justice (DOJ) warned Swiss banks in a statement last week that they took the risk of being targeted and prosecuted if they didn't join the programme.
Several Swiss banks, including Credit Suisse and Julius Baer, are already under formal criminal investigation in the United States. Their cases have been frozen pending a solution for the wider Swiss banking sector.