BERN — US clients of UBS with more than 250,000 Swiss francs (165,641 euros, 248,040 dollars) in assets could have their details turned over to US tax authorities if there is proof of fraud, Swiss authorities said on Tuesday.

For those who have simply not disclosed their accounts, their records would only be provided to US tax authorities if the account held more than one million francs at any time between 2001 and 2008, the Swiss Federal Office of Justice said here.

In addition, Switzerland may also provide details on undeclared accounts that generated more than 100,000 francs every year over a period of three years, it added, publishing details of a deal between Washington and Bern.

UBS, and the US and Swiss governments, in August signed agreements ending months of diplomatically sensitive negotiations over a massive US probe of taxpayers with secret accounts at the world's largest wealth manager.

Under the out-of-court settlement for a lawsuit, UBS agreed to disclose up to 4,450 names of American clients to US tax authorities.

Current legislation requires UBS to pass these details to the Swiss government, which in turn would decide if they should be transmitted to the United States.

A special team set up by the Swiss authorities received the first 500 clients dossiers from UBS by the end of October.

"Final decisions are being issued on an ongoing basis, meaning that the first can be sent out as early as today," the justice office added.