Pressure on the Government Pension Investment Fund to buy more stocks will benefit the public as well as boost equity markets, according to the head of a panel that advised on overhauling the world's biggest retirement fund.

"Some are concerned the GPIF reforms are a way to raise stock prices, but actually they're for pension recipients," Takatoshi Ito told the Liberal Democratic Party in Tokyo on Tuesday. "Improved returns would lead to lower future pension premiums and a higher level of future benefits."

The ¥128.6 trillion GPIF is under pressure to overhaul its investment strategy as Prime Minister Shinzo Abe and the Bank of Japan seek to revive the world's third-biggest economy and exit deflation. GPIF should not be used as a tool to push up stock prices and pressure to do so is unfair, Takahiro Mitani, the fund's president, told the Financial Times newspaper last month.