The Hanover Insurance Group,a provider of property and casualty insurance, has reported net loss of $31.8m or $0.70 per share, for the second quarter of 2011, compared to net income of $2.3m or $0.05 per share, for the same quarter previuos year.

Net premiums written for the quarter were $815.4m, an increase of 1.7% compared to $802m in the prior year period.

The pre-tax net impact of catastrophes was $156.7m in the second quarter of 2011, compared to $85m in the second quarter of 2010.

The company posted a loss of $24.7m in commercial Lines pre-tax segment for the second quarter of 2011, compared to pre-tax segment income of $16.9 in the prior-year period.

Catastrophe-related losses were $77.1m, or 18.9 points, of the second quarter combined ratio in 2011, compared to $25.7m, or 7.8 points, in the prior-year quarter.

The Hanover CEO Frederick Eppinger said an unprecedented number of tornadoes and extreme weather in the US resulted in a net loss for their company this quarter.

"Our underwriting results, excluding catastrophe losses, continued to generate improved results driven by more favorable accident year loss ratios, coupled with an improved expense ratio in our Commercial Lines business," Eppinger said.