Vic fire sparked by lightning: Report

A fire that destroyed 116 homes on the Victorian surf coast was not caused by burning off, according to a state government report.

The report, penned by inspector-general for emergency management Tony Pearce, found the Wye River-Separation Creek fire was sparked by a lightning fire along the Jamieson Track and was not caused by back-burning.

United Firefighters Union secretary Peter Marshall called on an independent review of the Christmas Day fire by the coroner.

"We know for a fact some very senior fire officers who were involved in the fire fight have not been questioned or enabled to tell their side of the story to the person that wrote this report," he told AAP.

The Wye River bushfire burned more than 2500 hectares before it was contained on Thursday, with firefighters saying it will take torrential rain to extinguish it completely.

The inspector-general's full report is due on February 12.