It was when a pipe system was to be pressure tested at the battery factory that the accident occurred.
Four people ended up in a gas cloud with ammonia but managed to run away, something that SVT reported about earlier.
- Very shocked with watery eyes and noses, we went coughing and panting further through the room, said a person in the report to the Swedish Work Environment Authority.
No person was seriously injured in the accident.
But neither MSB, the supervisory authority Länsstyrelsen nor the municipality's rescue service were informed of the incident.
Northvolt: Misjudgment was made
The county administrative board in Västerbotten has now reported Northvolt in Skellefteå to the police, Dagens Arbete reports.
The accident is being investigated by the National Unit for Environmental and Work Environment Objectives, which has started a criminal investigation regarding suspected obstruction of environmental control and unauthorized environmental activities.
Northvolt states for Dagens Arbete that an initial assessment was made in connection with the ammonia accident.
- An assessment was made that the discharge was of a minor nature and therefore not subject to reporting to the County Administrative Board, which was incorrect, says Anders Thor, responsible for public relations at Northvolt to Dagens Arbete.