* Affects French nationals holding French securities
* Other nationals holding French stocks/bonds also affected
* Bank to seek client authorisation
* Move unrelated to recent Switzerland-France tax treaty
(Adds details, comments from bank)
ZURICH, July 1, (Reuters) - Swiss bank Credit Suisse said on Wednesday it will pass the names of clients holding French securities to the French markets authority.
Partly confirming an article in Swiss daily Le Temps, a Credit Suisse spokesman said the bank, one of the world's biggest wealth managers, has sent a letter to French clients holding French stocks or bonds.
The letter sought authorisation to pass on information to the Autorite des Marches Financiers (AMF), the financial markets regulator, he said.
In a later communication a spokesman for the bank said the AMF could also request information on non-French nationals holding French securities, and said non-French clients holding French securities would also be contacted.
"We have to be in a position to disclose this information if required to do so by the AMF," he said.
A source with knowledge of the French regulator said the AMF has had the authority to request such information for some time, although to date it has not enforced such disclosures.
Access to Swiss banking client names is a sensitive issue with Peer UBS currently locked in a battle with U.S. regulators to preserve the identity of the names of thousands of its Swiss bank clients amid a global crackdown on tax havens.
Credit Suisse said the request for clients to authorise disclosures on details such as the beneficial owner of French securities and their trading records was not related to a tax treaty signed by Switzerland and France in June.
The Credit Suisse spokesman said an assertion in Le Temps that the bank would hand over clients' details to French tax authorities was wrong, although the tax authorities could access the data from the AMF if required as part of a criminal investigation.
The newspaper quoted a Credit Suisse letter to relevant clients dated June 24 as saying those who refused to be identified or who did not reply before September 1 would have their French securities sold at the prevailing market price. (Reporting by Martin de Sa'Pinto; editing by John Stonestreet and Mike Nesbit)