Updated

The Energy Department's inspector general says federal energy regulators improperly allowed widespread access to a document outlining physical threats to the nation's electric grid.

The official says in a "management alert" that the document created by the Federal Energy Regulatory Commission should have been kept secret as a national security matter. Instead it was provided to federal and industry officials in uncontrolled settings.

The Wall Street Journal reported last month that a federal analysis indicated that a coordinated terrorist strike on just nine key electric transmission substations could cause cascading power outages across the country.

Senators Mary Landrieu and Lisa Murkowski asked the inspector general to investigate the "apparent leak" to the newspaper. The Senate Energy Committee that Landrieu chairs is holding a hearing on the issue Thursday.