The U.S. government said on Sunday it was still prepared to step up its legal fight against UBS AG , to force the bank to reveal the names of thousands of Americans suspected of using it for tax evasion.

In a legal filing, shortly after announcing that it was seeking a delay in a court hearing in the matter set to open on Monday, the U.S. Justice Department said it would seek monetary sanctions against UBS if it refuses to hand over data on up to 52,000 secret accounts.

(Reporting by Tom Brown; Editing by Tim Dobbyn)