DETROIT (AP) — U.S. Transportation Secretary Anthony Foxx says there's no need to tell owners of recalled General Motors cars to stop driving them.

He says in a letter to senators that government engineers have found that if owners follow GM's advice, there's little safety risk to driving the cars.

GM is recalling 2.6 million small cars worldwide to replace ignition switches that suddenly can slip out of the run position and shut off the engine. That can knock out power-assisted steering and cause crashes. It also disables the air bags. GM says at least 13 people have died in crashes from the problem.

GM is urging owners to remove everything from their keychains. Foxx says that until the switches are replaced, the safety risk is "sufficiently mitigated" by an empty key ring.