New Zealand's approach to natural hazard risk will permanently constrain the economy if nothing changes, an insurer says.

New Zealand's approach to natural hazard risk is "ad hoc and piecemeal" and will permanently constrain the economy if nothing changes, the country's largest insurer says.

In a report published on Wednesday, IAG added its voice to a growing chorus of organisations calling for leadership from the government on how the country will deal with increasingly frequent, destructive weather disasters.

Research the company published earlier this year found that severe weather events now strike the country once every eight days on average.

The latest report said there were "concerning gaps" in New Zealand's ability to reduce the risks that natural hazards posed.