More evidence is needed to determine what set off Christchurch's devastating Port Hills fire in February

A fire investigation report has found the blaze began on private property, but it's not clear how.

It burnt through 650 hectares, destroying one home and damaging the Adventure Park.

Canterbury Police District Prevention Manager Inspector Ash Tabb says the investigation will re-open if more information becomes available.

He says they already have CCTV footage and have spoken to witnesses, so they'd need more to continue investigating.