By Jane Sutton

Prosecutors in Miami released a copy of a judge's brief order putting Weil on the court's fugitive list, but said they would have no further comment.

An indictment unsealed in November alleged that Weil and other unidentified bankers conspired to help 17,000 Americans hide $20 billion of assets in Swiss bank accounts in order to avoid paying U.S. taxes.

At the time, an attorney for Weil said he was innocent and called the indictment against him "totally unjustified."

Weil was based in Switzerland. He oversaw the Swiss bank's cross-border private banking business and was a member of UBS' executive board until stepping down when the charges were made public. UBS has said it was cooperating with investigators.

In November, UBS said it had discovered a few cases of tax fraud as part of the U.S. inquiry into whether it helped Americans dodge taxes through accounts in Switzerland.

Last week the bank said it was closing all the offshore accounts of its U.S. clients, as it came under pressure from U.S. tax authorities.

A Swiss newspaper, Sonntag, reported on Sunday that UBS expects a fine of some 2 billion Swiss francs ($1.8 billion) related to the U.S. tax investigation. A spokeswoman for the bank called the report "pure speculation."

Weil's failure to appear is bound to refocus attention on prosecutors' so far unsuccessful bid to jail alleged swindler Bernard Madoff while he awaits a possible indictment for fraud in what could the be largest Ponzi scheme in history.

In a Ponzi scheme, early investors are paid off with money from new clients.

In June, Samuel Israel III, a former hedge fund manager convicted of cheating investors out of $400 million, faked his own death to avoid a 20-year prison sentence. His high-profile run from justice ended after his mother persuaded him to turn himself in.

(Reporting by Jane Sutton; editing by Mohammad Zargham)