McDonald's has launched an investigation to try to figure out how much glass from a broken lightbulb could have potentially made it into its buns.
The fast-food giant shut about 50 of its 24/7 North Island outlets between about midnight and 3am on Saturday after a broken lightbulb was noticed on the floor next to the production line that makes the buns in the North Shore, McDonald's spokesman Simon Kenny said.
Suppliers said it was an extremely low risk, but could not guarantee the buns were glass-free.
Late on Friday night management made the decision to pull all buns from its restaurants which could have been contaminated.
That meant closing the stores, and then using the breakfast menu until restaurants were supplied with new buns.