"We are going to need to take account of these trends. Our estimate of exposure is increasing by 2 to 4 percent per year in terms of weather-related claims."

"We feel we have got a sufficient premium to take account of the risk of climate changes that have thus far occurred," he said.

According to the global insurance business of Allianz Group, some 35 to 40 percent of insured losses are due to natural catastrophes, mainly storms and floods.

A single major flood in Germany alone could cost 15 billion euros ($18.19 billion) in insured losses, it said. Damage from one flood in 2002 cost a gross 853 million euros.

The insurer noted that there were areas of high risk, for example around the Rhine where many firms no longer offer insurance.

Allianz and the WWF co-sponsored a 57-page report on the risks they say are posed by climate change and the investment opportunities that may be spawned by a drive for lower carbon emissions.

Concern about the so-called Greenhouse Effect has already helped drive exotic new markets such as weather derivatives, which already produces billions of dollars in turnover.

Insurers have been hit by a run of climate-related disasters such as the four hurricanes that devastated homes and businesses in Florida and last year.