A suspicious fire at a Dunedin school is being investigated by police.

Central Dunedin and Willowbank firefighters were called to Logan Park High School this morning, about 9am.

It appears the blaze broke out at the school because someone lit a paper dispenser on fire within a toilet block.

Six people were taken by ambulance to Dunedin Hospital, where they were treated for smoke inhalation.

The fire has not been classified as an arson at this stage, although investigations are continuing.