American International Group (AIG), the world's largest insurer by market value, said yesterday that second-quarter operating profit rose 13 per cent as worldwide life insurance operations grew strongly and premium rates in its core US business insurance market started to rise after almost a decade of decline. The New York-based company said second-quarter operating profit, excluding onetime items, rose to $1.43 billion, from $1.26 billion, in the yearearlier quarter.