Dunedin Railways says the steam train that is believed to have sparked 19 fires along 12 kilometres of track south of Oamaru yesterday was on loan from another company.
The 69-year-old locomotive was on a rare round trip from Dunedin to Oamaru, carrying about 400 people .
Crews from the Otago Rural Fire Authority remained on site to monitor the flames overnight.
Dunedin Railways' Chief Executive Murray Bond said they would investigate whether the train was at fault, and why the problems occurred when they did.
"So we're currently investigating the situation especially the locomotive, because this was a locomotive hired to Dunedin Railways."
Mr Bond said the train was hired from Mainline Steam.