A caravan tyre sparked a large scrub fire in Central Otago, leading the Fire Service to send out a helicopter, two fire engines, three tankers and some 25 firefighters.

Fire Service spokesman Andrew Norris said crews were alerted to the fire that was burning between the Goldfields Mining Centre and the entry to the Kawarau Gorge along State Highway 6 shortly before 6 tonight.

About 9.30pm he said the fire was around 100m long and went some 60m down into the gorge.

Mr Norris said nothing was at risk and the fire was contained, but crew would stay to dampen down the area.