A sign of Swiss banking giant UBS is seen at a branch in Zurich on October 26, 2018.

UBS Group, 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 2008-2009 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."

The U.S. Department of Justice did not immediately respond to a request for comment.

UBS said it had been advised by the Justice Department that the law enforcement agency intends to file the civil complaint.

It anticipates the Justice Department will seek unspecified monetary penalties regarding the mortgage securities, which date back to 2006 and 2007.

The lawsuit would be among the last actions over misconduct in the sale and pooling of mortgage securities which helped to cause the financial crisis.

The Department of Justice has settled similar claims with Citigroup, Deutsche Bank, JPMorgan Chase, Credit Suisse Group, Morgan Stanley, Goldman Sachs, Bank of America and Barclays.

Barclays settled for $2 billion in March after resisting a penalty the U.S. government sought near the end of the Obama administration in 2016. Justice had sought a much higher fine at the time and, when the two sides could not come to terms, the department filed a lawsuit.

More recently, HSBC Holdings agreed to pay $765 million last month to settle with the Justice Department over its sale of defective mortgage securities before the crisis, while major player Royal Bank of Scotland Group reached a $4.9 billion deal in May.