The Transport Accident Investigation Commission (TAIC) is looking into an explosion on Olivia, which was berthed in Bluff.
The accident happened at 4.30am last Saturday. Three people were taken to Southland Hospital.
A TAIC spokesman said the incident occurred while the Malta-registered bulk carrier was berthed at South Port.
Three crew members were working on a boiler in the engine room when there was an explosion or flashback, injuring all three.
The spokesman said one person had hospital-level burns while the other two crew members had only minor burns.
The status of all three was unclear yesterday.
According to the South Port website, the 12-year-old ship was moved to berth five at the port yesterday afternoon.
A three-person team - a former ship captain, another a senior engineer and the other a data extraction expert - from TAIC have been at the ship investigating the incident.
They had interviewed all members of the crew and any other people involved.
They had also taken photographs of the affected areas.
The TAIC would look into the incident but any report would be 18 months to two years away.
Most notifiable incidents at ports are investigated by Maritime NZ.
A Maritime NZ spokesman said it was investigating.
