The main railway line between Christchurch and Dunedin remains closed on Thursday. A train of 20 wagons derailed on Wednesday.
Nine of the wagons fell on their sides, and one carrying meat products burst.
KiwiRail says several crews are repairing the tracks. It says it's investigating the cause of the derailment, but believes it may have been a problem with one of the wagons.
The line is expected to reopen on Friday, and KiwiRail says it will add extra wagons to trains to clear the backlog.