Japan Post Bank Co. will invest up to ¥500 billion ($4.4 billion) in several foreign funds as part of efforts to diversify its profit sources, in response to the nation's low interest rate environment, the president of the bank's holding company said Wednesday.

Japan Post Holdings Co. President Masatsugu Nagato revealed the plan during a news conference in Tokyo, saying up to ¥300 billion will be invested in overseas funds that make loans to companies directly.

"We will participate with businesses looking to loan to medium-scale enterprises, which we have not done so far," through the new investment, said Nagato.

Japan Post Bank will select overseas funds specialized in making loans to promising medium-sized companies.

The banking unit of the Japanese postal group will invest the remaining ¥200 billion in foreign real estate funds, Nagato said.