Tasmania Police is investigating a fire on Bruny Island on Christmas Eve that caused more than $300,000 damage across three properties.

TFS Fire Investigators have identified where the fire started and have determined the Conleys Point fire was deliberately lit.

Kingston CIB will be investigating further with the assistance of uniformed police on Bruny Island.

Information can be provided anonymously by calling Crime Stoppers on 1800 333 000 or online at crimestopperstas.com.au