Fire has destroyed most of the infrastructure at Copersucar's sugar terminal in Brazil, one of the biggest in the world.

10 million tonnes of export capacity is expected to be offline for up to six months until repairs are made.

Santos port authority Codesp said the fire started in the conveyor system, which transports sugar through Copersucar's warehouses.

The fire subsequently spread through all of Copersucar's warehouses at its terminal after up to 300,000 tonnes of sugar ignited.

The blaze has been contained from spreading further by firefighters but would likely burn for another two days, Codesp said.

Copersucar officials said they had no additional information about the cause, containment and damage of the blaze beyond what the fire department and port authority has reported.

Television footage showed a three-storey high mountain of sugar engulfed in flames inside a warehouse that had lost most of its siding and roof to the flames.

Some of the overhanging conveyor belts that transport sugar between the warehouses and eventually to waiting ships appeared to have toppled over or were lying on the pavement alongside some of the warehouses.

When large stockpiles of sugar catch fire, it can be extremely difficult to extinguish it quickly.

As the sugar burns into the centre of the mound it creates a carbonized outer shell that inhibits the penetration of water and chemicals that would otherwise snuff out the blaze.

Firefighters will also have the challenge of dealing with subterranean passages that connect some of Copersucar's warehouses through which sugar is transported.