BEIJING, June 30 -- Absolute safety must be guaranteed as China considers diversifying its massive pension fund investments to bolster their value, the Ministry of Human Resources and Social Security (MHRSS) said Tuesday.

"The funding is used for retirees' daily lives and it cannot be jeopardized by big risks," MHRSS spokesman Li Zhong said at a press conference.

In China, urban employees pay for their pension before retirement and usually get a pension equal to about half of their previous salary.

Li said more than 2 trillion yuan (327 billion U.S. dollars) from the pension fund can be used for diversified investments.

Amid worries about the fund's low investment return over the past years, an official draft guideline released Monday gave the greenlight to invest in new channels, including the stock market, but restricts the maximum proportion of investments in stocks and equities to 30 percent of total net assets.

Money in the fund, roughly 90 percent of the country's total social security fund pool, was previously only allowed to be deposited in banks or invested in treasury bonds, which plays an important role in safeguarding its safety, but the investment channels are relatively restricted, said Li.

The guideline stipulates that the fund can also be invested in the nation's big projects and key enterprise equities, but restricts the maximum proportion of such investments to 20 percent of total net assets.