US-based global insurer Chubb says its first-quarter net profit grew 30%, driven by increased underwriting income.

Net profit reached $US656 million ($638 million), up from $US506 million ($492 million) in the previous corresponding period.

The combined ratio of 84.6% – compared with 90.2% a year earlier – reflects higher rates, a strong underlying underwriting performance and low catastrophe losses, according to Chairman, President and CEO John Finnegan.

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

Net written premium for the quarter grew 4% to $US3.1 billion ($3 billion), gaining 3% in the US and 6% elsewhere.

Chubb’s estimated gross and net losses from Superstorm Sandy remained unchanged; estimated commercial lines losses fell slightly and personal lines losses grew by a similar amount.