Japan's ¥135 trillion Government Pension Investment Fund is building up its alternative investment department after raising bets on infrastructure projects more than 10-fold to secure higher returns than low-yielding bonds.

The world's largest retiree fund has boosted staff in its alternative investment section, formed last year, to five people, Shinichirou Mori, director of the fund's planning department, said Friday in Tokyo. The fund is still trying to hire more people for the department, according to its website.

The fund's investments in infrastructure rose to about ¥70 billion at the end of September, based on figures supplied by GPIF, up from ¥5.5 billion at the end of March. The decision to invest in infrastructure is drawing interest abroad, with India's railway minister urging the nation to invest in rail projects there.