Ace Insurance says margin improvement in North America helped deliver a record third-quarter profit and a combined ratio of 86.5% for the nine months to September 30.

Chairman and CEO Evan Greenberg says global net property and casualty premiums grew 9% in the quarter, with growth in all insurance businesses and across global operations.

Third-quarter profit grew 43% to $US916 million ($948.38 million), while profit for the nine months was up 42% to $US2.76 billion ($2.86 billion).

Gross written premium for the nine months gained 6% to $US17.37 billion ($17.98 billion) and the underwriting profit increased 28% to $US1.44 billion ($1.49 billion).

Mr Greenberg says it was a more benign period for catastrophes, while the group also benefitted from better pricing and mix of business in North America and better product and geographic mixes internationally.