Large grass fire near Christchurch was caused by car 'bottoming out'

A large grass fire that was contained west of Christchurch airport was caused by a car 'bottoming out' while driving through a dip in the road, investigators say.

Two crews remain at the scene of the fire on Mcleans Island Road.

A fire investigator determined that a car 'bottoming out' created sparks which ignited grass on the roadside, and quickly spread.

FENZ began battling the blaze since 11 this morning, with seven crews containing the fire.

A firefighter operates a fire truck. Source: Luke Appleby/1 NEWS

There are no reports of any injuries.

In a Facebook post, FENZ said it was "a timely reminder that in hot and dry conditions, fires can start more easily and swiftly spread, rapidly becoming uncontrollable."

"Our advice, slow down on uneven roads, and avoid parking in or on long grass, as your hot engine could also start a fire,” the post read.