WASHINGTON – Federal safety regulators have asked DaimlerChrysler AG to recall 600,000 Dodge Durango and Dakota trucks because their wheels could fall off, a Chrysler spokesman confirmed Thursday.

The investigation involves Durango sport utility vehicles and Dakota pickups from the 2000 to 2003 model years. Chrysler spokesman Max Gates stressed that the vehicles haven’t yet been recalled. The company is planning to respond to the government’s request early next week, he said.

The National Highway Traffic Safety Administration made the recommendation, first reported by CBS News, after investigating reports of upper ball joint separation on dozens of vehicles. When the upper ball joint separates, the suspension can collapse and the wheel can fall off.

There are reports of several crashes but no injuries due to the issue in NHTSA’s investigation file.

Gates said Chrysler recognizes there is a problem with the upper ball joints, but “we do not think it rises to the level of a safety defect.”

Gates said a vehicle owner would hear noise coming from the vehicle well before the upper ball joint failed. Mechanics also will find out if an upper ball joint needs repaired during routine maintenance, Gates said.

Gates said if the upper ball joint fails, it is most likely to happen at low speeds and during turns.