DETROIT (AP) ― General Motors is boosting by 971,000 the number of small cars being recalled worldwide for a defective ignition switch, saying cars from the model years 2008-2011 may have gotten the part as a replacement.

The latest move brings the total number of cars affected to 2.6 million. The questionable handling of the problem, including GM’s admission that it knew the switches were possibly defective as early as 2001, has embarrassed the nation’s largest automaker. The recalls ― which are under investigation by Congress and federal regulators ― have overshadowed the improved quality of GM’s newer cars.

The episode has also consumed the time and efforts of GM’s new CEO, Mary Barra, in her first few months on the job. Barra has apologized publicly for the deaths linked to the switch defect and ordered what she promises will be an “unvarnished” internal investigation of the matter.

GM previously announced the recall of 1.6 million cars, only through the 2007 model year, which were built with the faulty switch. The recall involves six cars: the Chevrolet Cobalt, Chevrolet HHR, Pontiac G5, Pontiac Solstice, Saturn Ion and Saturn Sky. 

GM says it sold 95,000 faulty switches to dealers and aftermarket wholesalers for use as replacement parts. Of those, 90,000 were used to repair vehicles from the 2003-2007 model years. But 5,000 of the switches were used to fix cars from the 2008-2011 model years.

GM said it doesn’t know which cars got those 5,000 switches, so it needs to recall all of them. Of the cars being added to the recall, 824,000 were sold in the U.S.

The ignition switches can move out of the “run” position and cause the car’s engine to stall. It can also knock out power steering and power brakes, making the vehicle harder to maneuver, and disable the air bags. GM has said the defect is linked to at least 12 deaths in cars from the 2003-2007 models years. On Friday, the company said it isn’t aware of any fatalities connected to the defect in the 2008-2011 models.

“We are taking no chances with safety,” Barra said in a statement.

Barra is scheduled to testify before two congressional committees next week. The committees want to know why it took GM more than a decade to recall the cars after engineers discovered the faulty switches. The Justice Department is also investigating.

GM has said that it expects to have replacement switches starting next month for the cars originally included in the recall. GM expects those repairs to be completed in October.

The company said owners of the cars added to the recall Friday will be contacted the week of April 21.

Until the recalls are performed, the company says drivers should remove everything but the key from their key chains, to avoid pulling the ignition switch out of the “run” position.