President Barack Obama has called last week's Boston bombings an "act of terror," but businesses near the blast site may have a vested interest in keeping that designation unofficial.

Companies could lose insurance payouts for property, lost income and other damage if the bombings are officially declared an act of terrorism by key U.S. officials, under an 11-year-old law that hasn't yet been tested, according to industry executives and lawyers, as well as city and business leaders in Boston.

The reason: After the Sept. 11, 2001, terrorist attacks, policies sold to business customers typically haven't covered losses stemming from "terrorism" unless the customer pays extra for the coverage. The 2001 attacks resulted in about $40 billion in insured damages, when measured in today's dollars.

If there is no terror finding, damages would be covered in general under regular property-and-casualty policies, said Robert Hartwig, president of the trade group Insurance Information Institute.

"We have been working with the mayor's office, and we've been told the city is exploring all the different possibilities as far as the federal government is concerned as to what is available" in federal aid, and talks also have included the categorizing of the event," said Meg Mainzer-Cohen, president of the Back Bay Association, a local business group.