ZURICH—Natural disasters in the Asia-Pacific region will cost Zurich Financial Services Group around $500 million, the Swiss insurer said Thursday.

The pretax estimate is preliminary and is net of reinsurance, Zurich said in a statement.

The losses are from floods, storms and cyclone damage in Australia; the Christchurch, New Zealand, earthquake and the earthquake and tsunami that struck Japan.

The losses will be recorded in Zurich’s first-quarter results, which are scheduled to be released May 5, the insurer said.

The ultimate cost of the disasters will take some time to compile because of the extreme nature of the losses and limited access to the damaged areas, particularly in Japan and New Zealand where earthquakes caused extensive damage, Zurich noted.