About 30 people were on site at the time and evacuated when the alarms sounded.
"The small fire was detected and put out quickly by operational staff at site. They were able to do this before the fire and ambulance services arrived which is a real credit to the team who worked together incredibly well to manage this incident," Kattera said.
How the fire started was being investigated today.
"We are investigating the root cause but can confirm that it wasn't a gas explosion nor an electrical fault," Kattera said
Production stopped for a couple of hours so the incident could be managed.
The plant had been scheduled for cleaning so that was carried out and began operating again about 1.30am today.