DETROIT - U.S. safety regulators have opened a preliminary investigation into reports that fuel tanks from 1997 to 2001 model year Ford Motor Co. F-150 pickups have dropped onto the road due to rusted support straps, Reuters reported.

"This presents a fire hazard from leaking gasoline as well as an obstruction hazard to vehicles following the subject trucks," the U.S. National Highway Traffic Safety Administration said in a notice posted on its Web site.

Ford is cooperating with the government as it investigates the reports, spokesman Wes Sherwood said on Monday.

Investigators received 32 reports of corrosion, including 28 where one or both straps supporting the fuel tank had broken, causing it to drag on the ground or detach from the truck, NHTSA said.

There were six reports of fuel spills among the complaints, but no fires or injuries, NHTSA said. The investigation covers about 1.4 million pickup trucks and was opened on September 7.