General Motors told its dealers to stop selling any Chevrolet Cruze cars equipped with 1.4-liter turbo engines on their lots.

The automaker did not provide any information why it issued the order. Automakers typically halt sales of a car if they learn of some safety defect. Sometimes it can be a minor issue that puts the model out of compliance with federal safety regulations.

At the same time, 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 stop sale order is for 2013 and 2014 model year Cruze sedans with the gasoline turbocharged engine, not the diesel version, said Alan Adler, a GM spokesman. It amounts to about a third of the Cruze inventory at Chevrolet dealers.

"No other details to share," he said.

The Cruze is GM's bestselling compact car in the U.S. It sold nearly 250,000 last year, making it one of the top-selling vehicles in America.

The company 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," GM CEO Mary Barra said in a statement.

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.

The Los Angeles Times and Associated Press contributed to this report.