WASHINGTON, May 17 (Reuters) - U.S. safety regulators have upgraded an investigation involving 65,347 Kia Sorento sport utility vehicles after receiving consumer complaints that the optional glass sunroof had shattered.
The National Highway Traffic Safety Administration has upgraded its probe to an engineering analysis from a preliminary evaluation, which was opened in October, according to documents filed online.
The agency said it has received 26 consumer complaints about sunroofs spontaneously shattering in the South Korean automaker's Sorento SUVs from model years 2011 to 2013. Of those, 24 occurred while the vehicle was in motion.
In four cases, occupants suffered minor cuts from the shattered glass, according to NHTSA.
"Kia stated in its response that their field inspections identified only one potential cause for the sunroof breakage - external impacts from rocks or other foreign objects encountered while the vehicle was in motion," NHTSA said.
The agency said, however, that it upgraded the investigation because it found the number of incidents "concerning."
Kia was not immediately available for comment.
An engineering analysis is a step in a process that may lead to a recall should regulators determine that a manufacturer needs to address a safety issue.
(Reporting by Eric Beech; Editing by Bernard Orr)