The National Highway Traffic Safety Administration said Monday that it is investigating whether Graco took too long to report a safety defect in its child car seats.

Graco Children’s Products Inc., a division of Atlanta-based Newell Rubbermaid Inc., recalled 6.1 million car seats this year because the buckles could get stuck. That could put a child’s life at risk in an emergency. It is the largest child seat recall in U.S. history.

Federal rules require a manufacturer to report a safety defect within five days of becoming aware of it. If the investigation finds the company failed to report the defect in a timely manner, the company could face up to $35 million in fines.

A Graco representative could not be reached immediately for comment Monday. The company has previously said there have been no injuries reported because of the problem.

The agency and the car seat maker were involved in an extended dispute over the car seat recall.

When Graco recalled 4.2 million toddler seats in February, the NHTSA sent a letter that sternly questioned why infant car seats weren’t included and accused the company of soft-pedaling the recall with “incomplete and misleading” documents for consumers. The company gave in to regulatory pressure and recalled 1.9 million infant car seats in July.

(AP)