By John Miller

ZURICH (Reuters) - Switzerland said it plans to give information to U.S. tax authorities about accounts at HSBC Holdings Plc's <HSBA.L> Swiss private bank, as part of a U.S. investigation into tax evasion.

HSBC's Swiss unit has already paid tens of millions of dollars in fines after admitting substandard compliance on tax evasion and other issues.

The Swiss government said it made the announcement about its plans on Tuesday to alert HSBC account holders whom it has been unable to locate, and to give them the chance to lodge a legal appeal if they object to having their information sent to the U.S. Internal Revenue Service (IRS).

The move comes after the IRS asked Swiss tax authorities in April for assistance on HSBC Private Bank (Suisse) SA accounts held by Swiss-registered "domiciliary companies" with U.S. beneficial owners between 2002 and 2014.

The Swiss Federal Tax Administration said the IRS targeted HSBC accounts "where there is evidence that the U.S. beneficial owner exercised control, directly or indirectly, over the account in violation of corporate governance ... by withdrawing funds from the account for personal use."

HSBC said it was cooperating.

"Following an information request in April 2016 from U.S. authorities to the Swiss Federal Tax Administration (SFTA), the bank has provided certain files, mostly related to former clients, to the SFTA," said Lonnie Frisby, a spokesman for HSBC's Swiss private bank. "The Swiss authorities may forward part or all of this information to U.S. authorities in accordance with applicable laws and treaties. Anyone subject to this request has been notified."

The U.S. Department of Justice is also investigating Britain-based HSBC over its Swiss unit's role in helping wealthy U.S. citizens evade taxes.

A spokesman for Switzerland's tax agency in Berne declined on Tuesday to say how many HSBC accounts were involved in the IRS request, citing Swiss privacy laws.

No account holders were named in the Swiss notice. The notice indicated the IRS was seeking details of accounts in excess of $50,000 where there were discrepancies on tax forms meant to help the IRS determine who could benefit from the accounts.

POSSIBLE APPEALS

With Tuesday's formal notification in Switzerland, HSBC account holders now have 30 days to lodge an appeal.

Such appeals would be handled by Swiss courts.

Switzerland's announcement that it was moving to help the IRS with the HSBC accounts came as the country received an overall rating of "largely compliant" in an international review of how well it shares information with other countries on tax matters.

HSBC's Swiss unit has been in the spotlight since 2008 when a former IT worker fled Geneva with files alleged to show evidence of tax evasion by tens of thousands of clients. French and Belgian authorities are also investigating possible tax fraud by account holders from those countries.

The group International Consortium of Investigative Journalists (ICIJ), which coordinated reporting on the leaked documents, said last year that a list of people who held HSBC accounts in Switzerland included sports professionals, rock stars and Hollywood actors, as well as dictators and weapons dealers. [http://tinyurl.com/hfds9v2]

Last year, HSBC acknowledged its Swiss subsidiary's failings, saying problems had emerged because the unit had not been fully integrated after its purchase in 1999.

In June 2015, the bank paid Geneva authorities 40 million Swiss francs ($41 mln) to settle a money laundering investigation.

HSBC has said it has since implemented more rigorous controls and is cooperating with tax authorities.

(This story corrects in paragraph 7 to clarify comment is from Lonnie Frisby, a spokesman for HSBC)

(Reporting by John Miller; Editing by Susan Fenton)