Moody's Investors Service said Friday it has revised upward its ratings of eight major Japanese insurance firms.

With an earlier upgrade of Asahi Mutual Life Insurance Co., the revision pushed up the average insurance financial strength ratings of the nine traditional life insurers in Japan to Baa2 from Baa3.

The upgrades of the eight reflect Moody's positive views on the recent enhancement in the insurers' operating environment and the overall improvements in stabilizing their financial fundamentals since 2002, when Moody's adjusted ratings downward, the U.S. credit-rating agency said.

The eight insurers are Dai-ichi Mutual Life Insurance Co., with a rating of A3; Daido Life Insurance Co., with A3; Fukoku Mutual Life Insurance Co., with Baa1; Meiji Yasuda Life Insurance Co., with A3; Mitsui Life Insurance Co., with Ba1; Nippon Life Insurance Co., with A1; Sumitomo Life Insurance Co., with Baa3; and Taiyo Life Insurance Co., with Baa1.

According to Moody's, the negative factors, including investment losses and high lapse and surrender rates from 2002 to 2004, have recently seemed to recover. This change contributed to the operating environment and to recent stabilization in earnings and capitalization.