US seeks light sentence for UBS client in tax case

* Former UBS client pleaded guilty to tax evasion

* Testimony helped build case against Swiss banker

MIAMI, Oct 26 (Reuters) - The U.S. government asked for a reduced sentence on Monday for a former American client of UBS AG (UBSN.VX: Quote, Profile, Research) who pleaded guilty to tax evasion but provided information leading to the indictment of a Swiss banker and a Zurich lawyer.

The request came in a court filing ahead of Friday's scheduled sentencing in Fort Lauderdale, Florida of Jeffrey Chernick, who acknowledged in July that he used Swiss bank accounts, including one at UBS, to hide more than $8 million from U.S. tax authorities.

Chernick will be one of the first U.S. clients sentenced as part of a wide-ranging probe into UBS, the Swiss bank that settled a U.S. criminal probe earlier this year by paying $780 million and admitting it helped U.S. citizens evade taxes.

The Swiss bank giant ended a related civil lawsuit in August by agreeing to turn over the names of 4,450 wealthy U.S. clients with undisclosed offshore accounts.

The court filing said Chernick's cooperation with U.S. authorities had provided "substantial assistance in the investigation of others who have committed offenses against the United States."

It added that his cooperation also led to a conspiracy indictment in August of Swiss banker Hansruedi Schumacher and lawyer Matthias Rickenbach, who were charged in a south Florida court with encouraging Americans to switch secret accounts from UBS to Neue Zuercher Bank (NZB), a private bank, to conceal their wealth.

The two allegedly argued that NZB would be better protected from U.S. tax authorities because it did not have operations on American soil.

"Based upon information provided by the defendant (Chernick) and the indictment of Schumacher and Rickenbach, the Swiss government has opened a criminal investigation into allegations contained in the indictment," the court filing said

Because of his cooperation, government prosecutors asked the Fort Lauderdale court to impose a sentence on Chernick at the lower end of the guideline range of 18 months to 24 months. (Reporting by Tom Brown; Editing by Gary Hill)