Sumitomo Life Insurance, Japan's fourth-largest private-sector life insurer by premium income, has reached advanced stage of discussions to acquire a 40% stake in the life insurance unit of PT Bank Negara Indonesia.

Sources familiar with the matter were quoted by Reuters as saying that the transaction could be valued at nearly $400m. The final price is yet to be finalized.

Currently, the two sides are discussing conditions for exclusive talks, after a bidding process in which Sumitomo Life emerged as the sole remaining suitor, the sources told the news agency.

Earlier this year, Sumitomo Life also tried to bid for a 15% stake in Thai Life Insurance Co; although its rival Meiji Yasuda Life Insurance clinched that deal for nearly $700m.

Japanese financial organizations, especially insurers have been looking for assets acquisition in Southeast Asia, where an emerging middle class is boosting the growth prospects for the insurance market.