Underwriting losses for the US property and casualty industry continued to mount in the first quarter of 2011, new statistics show.

A report from the US Insurance Statistics Office (ISO) and the Property Casualty Insurers Association of America (PCI) shows net losses on underwriting plummeted to $US4.5 billion ($4.3 billion) from $US1.8 billion ($1.7 billion) for the first quarter of 2010.

Insurers’ combined ratio also deteriorated to 103.3% for the quarter, compared to 101.1% in the first quarter of 2010.

This was despite an increase in net written premiums to $US108.6 billion ($103 billion) for the quarter, up from $US104.9 billion ($99 million) in 2010.

“The 3.5% increase in total industry net written premiums in first-quarter 2011 was the first increase in first-quarter net written premiums since 2007 and the largest since 2004, when first-quarter net written premiums rose 4.8%,” says Michael Murray, ISO’s Assistant VP for Financial analysis.

Investment gains partially offset the deterioration in underwriting results but net income after taxes still dropped from $US8.9 billion ($8.4 billion) for the first quarter of 2010 to $US7.8 billion ($7.4 billion) in first quarter of 2011.

Looking ahead, PCI data as of June 20 shows that with the quarter yet to close, catastrophes striking the US in the second quarter have already caused $US14.7 billion ($13.9 billion) in direct insured losses to property.

This is more than double the $US6.4 billion ($6.1 billion) in direct insured losses from all the catastrophes that occurred in the second quarter of 2010.