Thu May 24, 2007 7:22PM EDT

DETROIT (Reuters) - Nissan North America (7201.T: Quote, Profile, Research has a warning for customers: placing your electronic key too close to your cellphone could leave you stranded.

The automaker is asking customers driving new models of two of its flagship sedans to keep their car keys and cellphones at least an inch apart to avoid disabling the "intelligent keys."

Cellphones kept near Nissan's I-Keys -- wireless devices designed to allow drivers to enter and start their cars at the push of a button -- can erase the electronic code on the keys, rendering them unable to unlock or start the cars.

The problem has occurred on the 2007 Nissan Altima and Infiniti G35 sedans --two of their top-selling models, the company said on Thursday.

"We discovered that if the I-Key touches a cellphone, outgoing or incoming calls have the potential to alter the electronic code inside the I-Key," Nissan spokesman Kyle Bazemore said.

"The car won't start and the I-Key cannot be reprogrammed," he added.

The problem has occurred in a "very small percentage" of cars sold, Bazemore said. He also said a new version of the I-Key would be available in the fall.

Bazemore said current owners have been notified of the potential glitch via mail and can get new keys from dealers if they encounter the problem.