(Reuters) - Lloyd's of London underwriter Hiscox Ltd HSX.L said it now estimates net claims for Hurricanes Harvey, Irma and Maria to total around $225 million, having previously estimated the same amount for Harvey and Irma alone.

FILE PHOTO: A car dealership is covered by Hurricane Harvey floodwaters near Houston, Texas, U.S. on August 29, 2017. REUTERS/Rick Wilking/File Photo

The insurer, which underwrites a range of risks from oil refineries to kidnappings, also said claims arising from the Mexico earthquakes and California wildfires are not expected to be material for the group.

The third quarter of 2017 is expected to be the costliest on record for the insurance and reinsurance industry due to the run of natural catastrophes, with policy rates expected to go up as a result. However Hiscox seems so far to be weathering the impact better than some rivals.

The underwriter reported gross written premiums for the first nine months rose 12.4 percent to 2.09 billion pounds ($2.75 billion), helped by its Hiscox USA business.

As insurers report the full extent of the damage in their third-quarter results in coming weeks, investors will be looking for signs they can claw back some of those losses by raising premiums for customers.

A turnaround in prices would be the first major reversal since Hurricane Katrina in 2005, the costliest natural disaster in U.S. history.

“The recent catastrophes are estimated to have cost the industry $100 billion and follow a decade of rate reductions. Therefore, it is not surprising that we are seeing signs of a hardening market,” Hiscox said.

Hiscox said it was seeing price increases of between 10-50 percent for loss-affected and exposed U.S. property lines, while rate reductions on London Market insurance lines are coming to an end.

It added that for its U.S. catastrophe-exposed reinsurance business, it expects double-digit increases in rates during January renewals.

However insurance and reinsurance broker Jardine Lloyd Thompson JLT.L said on Tuesday that it did not expect the recent series of natural disasters to have an impact on its 2017 "outturn". It added that it was "premature" to draw conclusions on the insurance rating environment.

Hiscox also said on Tuesday that demand has risen for FloodPlus,an alternative to the National Flood Insurance Program (NFIP)it launched in 2016, following Hurricane Harvey.

“Harvey has taught us a lot about the responsiveness of this product and we have seen strong increase in demand. We believe the opportunity to write more U.S. flood business is significant,” the insurer said.

The underwriter added that a recent U.S. tax reform bill which seeks to levy a 20 percent excise tax on payments made to foreign affiliates, could have an impact on its “internal group reinsurance arrangements”.