Smoke billowing into the sky in the vicinity of Canterbury's Eyrewell forest is thought to be a controlled burn on a farm.
A Christchurch City councillor, Deon Swiggs, has posted a picture of it.
"Looks like a fire of some sort has just started around the Eyrewell Forest or Eyreton area," he wrote. "Picture taken from the Waimakariri River near West Melton."
A Fire and Emergency NZ spokesman said: "It looks like a controlled burn by a farmer. We are still trying to get to the bottom of it."