NHTSA is looking into loss of power and stalls in TDI variants of the Golf, Jetta and Audi A3 models.

Some Volkswagen Group's TDI engines are under review by the NHTSA (National Highway Traffic Safety Administration) in the United States for suspected fuel-pump flaws.

Regulators began investigating the TDI engines that go into both VW and Audi brand vehicles after reports of engine stalls, some even occurring at highway speeds. Those reports include one accident and 160 complaints about loss of power and stalls lodged by vehicle owners and by VW itself.

According to the NHTSA website, those incidents are possibly related to failing high-pressure pumps that can contaminate the fuel system with debris. The website said that about half of the stalling incidends occurred at highway speeds with no restart of the engine.

The review will cover over 97,000 vehicles and includes the 2009 and 2010 model-year Jetta, Golf and Audi A3 with TDI clean-diesel technology.

The government body will conduct its own engineering analysis to assess whether a recall should be ordered.

"We take these matters very seriously and are cooperating fully with NHTSA during its investigation," said a U.S.-based VW spokesperson.