Police investigate cause of SA bushfire

South Australian police investigating the cause of the recent major Sampson Flat bushfire are visiting bushland adjacent to where the blaze is believed to have started.

The focus of the investigation has so far centred on an incinerator on a private property, police say.

The Country Fire Service on Thursday will help police in the search for locations in the Adelaide Hills where spot fires started from the initial ignition point.

A police helicopter will help guide those carrying out the search.

The fire, which began on January 2, destroyed 27 houses and damaged many other structures.