TOKYO (REUTERS) - The operator of McDonald's in Japan said on Wednesday it had found no link between a Thai plant and the plastic found in a chicken nugget earlier this month that sparked an uproar over product safety at the fast-food chain.

McDonald's Holdings Co (Japan) Ltd said an investigation showed the plant in Thailand did not use the same plastic material as the type found in the McNugget by a customer in Misawa in northern Japan.

It also found that plant employees were following the proper procedures for checking their belongings when entering the facility.

The company said the Misawa store did not use that type of material, either, and believes the possibility is low that the plastic entered the nugget during the food preparation stage at the store. It was thus unable to determine the origin of the plastic.