Following last week's fiery train crash in North Dakota, the federal government Thursday issued a safety alert that crude oil being transported from the Bakken region, which stretches through swaths of North Dakota and Montana , is more flammable than traditional heavy crude.
The Pipeline and Hazardous Materials Safety Administration said it issued the alert to notify the public, emergency responders, shippers and carriers as a result of its preliminary inspections after recent train derailments and resulting fires in North Dakota, Alabama and Canada.
(Read more: Train collision forces N. Dakota town evacuation )
The most serious of these derailments was the Lac-Megantic, Quebec accident, where a runaway train, sped into the town and crashed into a night club, killing dozens last summer. The PHMSA, part of the Department of Transportation, said it is reinforcing the requirement that hazardous materials be properly tested, characterized, classified and where necessary, degasified.
The PHMSA, along with the Federal Railroad Administration, as part of its investigation have begun a compliance initiative involving unannounced inspections and testing of crude to verify that they have been properly classified.
-By CNBC's Patti Domm. Follow here on Twitter @pattidomm.