At the heart of that was New Zealand's seismic risk and its very small percentage share of the world's earthquake and natural disaster premium market.
These were forcing the world's leading reinsurers to review their long-term reinsurance commitment to New Zealand.
"With only 0.2 per cent of the world's earthquake premium market to attract buyers here, plus the fact New Zealand is now a well-defined seismic risk, these factors represent the biggest threat to sustainable and long term reinsurance cover for this country,'' Ryan said.
The trend was also being seen in countries such as Australia, the United States and Japan.
"These jurisdictions have all suffered similar large-scale natural disaster events, earthquakes, major flooding and tsunami events. If reinsurance has returned to these markets it has been at the expense of traditionally cheaper premiums.
"What has happened in these places is a forerunner of what may happen here with reinsurance cover and ultimately dearer premiums for earthquake and natural disaster coverage,'' Ryan said.