Volkswagen AG vehicles are under review by the U.S. National Highway Traffic Safety Administration after reports of engines stalls that may be related to fuel-pump failures.

The auto-safety regulator received reports of one accident and 160 complaints from owners and the company about engine loss of power and stalling, NHTSA said in a posting on its website Saturday. The power loss and stalling was related to high-pressure pumps failing and contaminating the fuel system with debris, the agency said.

About half of the reports involved stalling with “many of these alleging stall incidents at highway speeds in traffic with no restart,” the agency said.

NHTSA is reviewing model years 2009 and 2010 of the Volkswagen Jetta and Golf and the Audi A3 that have TDI clean-diesel engines, totaling about 97,272 vehicles.

The regulator, which received 52 of the complaints directly and the rest through the Wolfsburg, Germany-based automaker, upgraded its investigation to an engineering analysis, a step that can lead to a recall.

“We take these matters very seriously and are cooperating fully with NHTSA during its investigation,” Sheriece Matias, a U.S.-based spokeswoman for Volkswagen, said in an e-mail. “We will continue to work closely with the agency as the analysis continues.”

While confirming the investigation, officials at Volkswagen’s German operations, however, have ruled out engineering problems as the cause of the reported faults.

“Yes, there is an investigation,” Peter Thul, head of product communications at Volkswagen in Wolfsburg was quoted as saying by DPA. But he said the problem arose from filling the tanks of the diesel cars with the wrong fuel: petrol.

He denied there had been any such problems with the equivalent engines in cars running in Germany.

The Detroit News had quoted U.S. Volkswagen executives as saying even a small amount of gasoline in the diesel fuel may disrupt the necessary lubrication required and could cause the high-pressure fuel pump to fail.

But Thul said, “There is no fault in the engine’s design.” He said Europe’s biggest carmaker suspected U.S. owners had picked the wrong pump at gas stations, adding, “In 50 cars that were checked, 90 percent definitely had considerable amounts of petrol in the tank.”

(From news reports )