Japan Post Group is planning to expand its business collaboration with American Family Life Assurance Co. (Aflac) by sharply increasing sales outlets handling the U.S. insurer's cancer policies and jointly developing cancer insurance products, sources said.

The move by Japan Post, controlled by the government, is apparently intended to take into account U.S. concerns about Japan's insurance market, coming in the wake of U.S. opposition to a diversification plan envisaged by Japan Post's own insurance unit.

The opposition was expressed in the course of preliminary bilateral talks on the Trans-Pacific Partnership, a multilateral free-trade agreement.