Tokio Marine & Fire Insurance Co., Nichido Fire & Marine Insurance Co. and Asahi Mutual Life Insurance Co. are planning to form a comprehensive tieup with a view to integrating their operations in the future, company sources said Thursday.

If it goes ahead, the three-way alliance would be Japan's largest comprehensive insurance group, with combined assets of 19 trillion yen, and could trigger another wave of reconsolidation in the nation's insurance market.

The tieup, expected to be formally announced early next week, would also cross corporate group lines, since Tokio Marine is part of the Mitsubishi group and Asahi Mutual and Nichido Fire are members of the Mizuho Financial Group. The latter is to be set up later this month through the integration of Dai-Ichi Kangyo Bank, Fuji Bank and the Industrial Bank of Japan.