US-based global insurer Chubb has raised its earnings forecast after first-half profit grew 33% on the corresponding period last year.

Net income increased to $US1.2 billion ($1.3 billion) from $US900 million ($971 million), aided by a 2% rise in net written premiums and higher investment revenues.

The combined ratio for the six months to June was 86.7%, compared with 92% a year earlier.

Catastrophe impact grew to $US237 million ($256 million) before tax in the second quarter – up from $US223 million ($206 million) – mainly because of severe storms in central US and storms and flooding in Alberta, Canada.

The improving combined ratio reflects higher premium rates and underlying underwriting performance, according to Chairman, President and CEO John Finnegan.

“We remain encouraged by the renewal rate increases we continued to obtain in all our business units,” he said.

Chubb has raised its operating income per share forecast to $US7.30 to $US7.50 ($7.87 to $8.09) from January’s prediction of $US6.40 to $US6.80 ($6.90 to $7.33).