Firefighting efforts are winding down for a huge scrub fire that broke out near Dunedin two days ago

It took helicopters, ground crews and heavy machinery to douse the flames.

A Fire and Emergency spokesperson says it was a roller coaster day for crews, with other duties and call outs in the region.

An investigation is under way into what started the blaze - which is being treated as suspicious

The spokesperson says they're hoping to be finished at the scene by midday.