Ford Motor Co recalled nearly 129,000 Ford Fusion and Mercury Milan sedans in the United States citing a risk that the wheels may fall off, U.S. safety regulators said on Friday.

These cars, from the model year 2010 and 2011, are equipped with 17-inch steel wheels. Ford said the wheel studs may fracture, causing the car to shake. If ignored, the wheels may fall off while the car is moving, according to a posting on the National Highway Traffic Safety Administration website.

The problems may be caused by steel wheel mounting pads or rear brake discs that have been incorrectly built and cannot properly support the wheel, Ford said.

As of September 30, Ford has found one case when the front wheel fell off and five cases where the rear wheel dropped off that are possibly due to these problems.

The cars were built at the Hermosillo stamping and assembly plant in Mexico from April 2009 and from December 2009 through November 13, 2010. Cars with alloy wheels are not affected.

Ford said 128,616 cars are affected by the recall.

(Reporting by Deepa Seetharaman in Detroit; Editing by Derek Caney)