WASHINGTON (REUTERS) - The US Department of Transportation has rebuffed a call by two Democratic senators to advise owners of 2.6 million recalled General Motors cars to stop driving them until they are repaired.

In a letter sent on Tuesday to Senator Edward Markey of Massachusetts, Transportation Secretary Anthony Foxx wrote that"such an action is not necessary at this time. Senator Richard Blumenthal of Connecticut joined Markey in the request.

It could take months for GM to replace faulty ignition switches in Chevrolet Cobalts, Saturn Ions and other models that have been linked to at least 13 deaths.