US tornadoes sent RenaissanceRe into a loss in the second quarter while PartnerRe has warned of extra losses from the Christchurch earthquake.

RenaissanceRe says $US70.8 million ($64 million) in losses from US tornadoes caused an operating loss of $US10.2 million ($9.23 million) for the quarter to June 30.

However, CEO Neill Currie says the company had a successful renewal season, and conditions are improving in its reinsurance segment.

“Our strong balance sheet, high ratings and leadership position in property catastrophe reinsurance allowed us to increase our catastrophe premiums by over 15%.”

Another Bermuda-based reinsurer, PartnerRe, has warned that it will incur a $US59 million ($53.3 million) loss due to changed catastrophe estimates in the second quarter, mostly due to the February Christchurch earthquake. The Bermuda-based reinsurer says its estimate from the Japan earthquake has not changed. It has previously disclosed $US89 million ($80.5 million) losses from tornadoes in the US in April and May.