The U.S. National Highway Traffic Safety Administration (NHTSA) has opened a preliminary investigation into 6.2 million General Motors Co. vehicles for possible corrosion of vehicle brake lines, the Detroit News reported.

NHTSA's investigation -- made public Monday -- includes 6 million 1999-2003 GM pickups and SUVs and 189,000 2003 2500 heavy- duty pickups. The investigation covers all models built -- not all models remaining on the roads -- so the actual number could be lower than 6.2 million.

NHTSA says it has received 110 complaints, including allegations of three crashes.

"The complaints allege the loss of braking effectiveness due to brake line rupture because of corrosion," NHTSA investigator Chris Lash said in a government filing. "In 37 of these complaints, the brake line failure was confirmed by a dealer inspection."

The owners allege that the crashes were caused by a corroded brake line.

GM spokesman Alan Adler said the company was working with NHTSA.

"We are aware of it and we are cooperating," the Detroit News quoted Adler as saying.

NHTSA received a March 2 petition seeking an investigation of 2003 Chevrolet Silverado 2500 HD pickups. The petition said the brake line corrosion "led to a large increase in stopping distance and with the brake pedal pushed to the floor."

The complaint said the incident happened after just six years of service and under normal driving conditions.