After nearly a year, residents are frustrated no one's been held accountable for the Port Hills fires.

This frustration has increased this week as Fire and Emergency NZ closes its investigation into the cause of the blaze.

The move is due to a lack of evidence, despite the agency believing the fires were deliberately lit.

Port Hills MP Ruth Dyson said the community is disappointed there hasn't been a conclusion yet.

"There was a life lost, there were several properties lost, and many hundreds of people had their lives disrupted. It was a really scary incident."

She said she suspects emergencies services are also disappointed.

"For someone to have deliberately lit those fires, which had such tragic outcomes and then no accountability, is frustrating for everyone."

Police say there is no evidence to conclusively show the fires were deliberately lit and their investigation remains open.