Upheaval in the domestic insurance industry continues as Nippon Life Insurance Co., Mitsui Marine & Fire Insurance Co. and Sumitomo Marine & Fire Insurance Co. plan to form alliances in areas including product distribution and computer system development.

The three insurers are eyeing eventually forming a comprehensive insurance group covering both life and nonlife insurance products, sources close to the companies said Sunday.

A formal announcement on the matter will be made in the coming days, the sources said. Nippon Life is the nation's top life insurer, while Mitsui and Sumitomo are Japan's third- and fourth-largest nonlife insurers.