Firefighters and five helicopters are tackling a fast-moving vegetation fire burning in North Canterbury.

Fire crews were called to the fire, between SH1 and the mouth of the Hurunui River near Cheviot at 1PM.

The fire is in the Dommett Road area and has burned at least 20 hectares.

It is not yet contained or under control.

Fire and Emergency is asking people not to stop to look at the fire as more crews are expected to arrive at the scene.