Millea, Japan's biggest insurance group, is set to buy Singapore-based Asia General, the holding company for two major insurers in southeast Asia, Asia Insurance and Asia Life Assurance.

Reports suggest that Millea is to pay in the region of Y50 billion ($426 million) to clinch the deal, thereby furthering its aims of expansion in the Asia-Pacific marketplace.

Millea is set to use its Tokyo Marine subsidiary to buy an initial 15% of Asia General, Bloomberg reports. The Japanese firm will then take full control next year. Millea is looking to diversify beyond Japanese shores as its home market has limited long term growth opportunities thanks to an aging population.

Millea has set itself a target of deriving at least a fifth of its profits from markets outside Japan from the current level of 4%, the Financial Times says. Asia General has operations in several countries in the region, including Vietnam and Malaysia as well as its native Singapore.