UBS , Switzerland's largest bank, said it expects to be sued by the U.S. Department of Justice as early as Thursday on civil charges related to the sale of mortgage-backed securities in the run-up to the 2008-09 financial crisis, according to a company statement.

The bank said the claims were not supported by the facts or the law and it would contest any such complaint "vigorously."

(Reporting by Karen Freifeld; Editing by Chris Reese) ((Karen.Freifeld@thomsonreuters.com;))