The Bank of Tokyo-Mitsubishi UFJ will invest around ¥100 billion in the Philippines' Security Bank, in its latest move to capitalize on growth in that nation's market, sources close to the matter said Thursday.

The main unit of Mitsubishi UFJ Financial Group Inc. plans to obtain a roughly 20 percent stake in Security Bank in a private allocation, becoming its second-largest shareholder. The Japanese bank is also considering having a presence on Security Bank's board, the sources said.

Facing a shrinking domestic market with Japan's aging population, major Japanese banks have turned to other countries for growth, with their revenues increasingly depending on overseas loans and investment banking business.

Sumitomo Mitsui Banking Corp., one of BTMU's main rivals, has obtained stakes in Cambodia's Acleda Bank as well as Indonesian bank BTPN, while Mizuho Bank has invested in Vietnam's Vietcombank.

BTMU acquired Thailand's Bank of Ayudhya in 2013 and is expected to seek further growth in Southeast Asia through mergers and acquisitions.