A fire in native bush and peat at Meremere in Waikato is now contained, and the rail line has reopened between Amokura and Whangamarino.
Fire and Emergency incident controller Thomas Harre said the fire covered about 5ha of native bush including peat alongside the main trunk railway line, which was closed temporarily.
The fire was visible from State Highway 1 but the road was not affected.
No structures were at risk and conditions were calm, which helped firefighting efforts.
Crews were on the scene overnight and this morning helicopters were used to support ground operations.
Harre said they were alerted to the fire just before 7pm and brigades have responded from both the Counties Manukau and Waikato Districts.
At its peak, 70 firefighters were on site, he said.
He said seven crews would remain to mop up the fire ground, but helicopters had been stood down.