The firefighters were called to help local Country Fire Authority volunteers with the blaze, which began about 3.30am Monday.

The damage bill to the hay export business is expected to be at least $1.5 million, and CFA incident controller Richard Bourke said the fire would continue to burn for at least the next few days.

"There are copious amounts of smoke still being produced," he said.

"One person estimated that it's down 40 per cent from the size it was, so there is 60 per cent to go and that will be smouldering over the next few days."

Mr Bourke said police and CFA investigators were again at the scene yesterday to find a cause of the fire.

He praised the work of volunteers.

"It's a fantastic effort from the volunteers to work throughout the day and throughout the night and they all do their bit," he said.

It was estimated at least 2000 tonnes of hay and several pieces of machinery were burned in the fire.