While the cost of property insurance in peak hurricane zones in the US continue to rise, premiums in many other lines are under downward pressure, according to global insurance broker Aon Corp.

At a press briefing in London yesterday morning, Aon said prices remained firm for reinsurance, but that falling prices in primary insurance usually leads to a drop in reinsurance rates too.

Charlie Cantlay, deputy chairman of Aon?s reinsurance brokerage unit, was quoted by the Wall Street Journal yesterday as saying reinsurance pricing wasn?t ?silly,? , but he noted that premiums ?have peaked? across the industry and are slipping to various degrees.

The price of primary airline coverage, for instance, has fallen up to 20 percent and property coverage outside the US is down 10 percent to 15 percent, Aon said. Reinsurance rates have fallen less in both areas but could be pressured if insurers ? reinsurers? clients ? keep lowering prices.

Insurance pricing tends to rise and fall in cycles with supply and demand for coverage. Premium levels are closely watched ? particularly during the busy January 1 renewal season world-wide ? because a slide can indicate an ongoing price war.