(Reuters) - General Motors Co. said it had placed two engineers on paid leave as part of an investigation into defective ignition switches that led to a recall of 2.6 million cars.

"This is an interim step as we seek the truth about what happened," Chief Executive Mary Barra said in a statement.

GM spokesman Greg Martin said the company would not provide the names of the engineers. He did not give any other details.

At least 13 deaths in Saturn Ions, Chevrolet Cobalts and other car models have been linked to the faulty ignition switches, which can cause the engine to turn off suddenly, disabling the air bags and making steering and braking more difficult.

The National Highway Traffic Safety Administration is fining GM $7,000 a day for missing an April 3 deadline to provide information about the recall.

The regulator said on Tuesday that the automaker had not responded to over a third of its questions by the deadline.

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