A?plan to postpone retirement age is to be released in 2017, China's human resources and social security minister said yesterday.

It will be part of efforts to replenish the pension fund and maintain the labor force as the population ages, Yin Weimin told reporters on the sidelines of the national legislature annual session in Beijing.

The plan would be submitted for review next year, he said, before being officially released the year after. Implementation could come at least five years after that, he said, to "allow employees time for mental preparation."

The plan will be gradual, with retirement age raised by several months each year, he said. Under present arrangements, women can retire at 50 and men at 60, though people holding senior positions usually retire five years later.

Yin said the standard was outdated in relation to changing social conditions and life expectancy.

The plan's gradual implementation is to calm fears expressed when the idea was first mooted five years ago. There were concerns about the greater workload and lower pensions.

Yin did not state an eventual target age for retirement but economists expect it to be 65 within the next 30 years.

The pension fund is currently worth 3.06 trillion yuan (US$488 billion), but it is expected to be under growing pressure in coming years.

There are already deficits in some western regions as young people move to larger cities in the east for a better life leaving a greater proportion of the population as retirees.

Yin said a planning system for the pension fund will be set up this year to improve distribution and reduce risks.

The ministry will also expand investment options for the pension fund to include higher- return products.

"The future investments of the fund will be diversified to avoid putting all the eggs in one basket. Investments will include bank deposits, treasury bonds, projects with good prospects, among others," Yin said.

But safety would remain a top priority and there would be a ceiling on investment in riskier assets.

Currently, the fund is allowed to put money only in treasury bonds and bank deposits. The annual return for the pension fund has been 2 percent in recent years, lower than the current benchmark one year deposit rate of 2.5 percent.

Yin attributed the low return to limited investment options and non-market-oriented management. He said the ministry will submit the new investment plan later this year, and professional investment management institutions will be commissioned to improve returns and avoid potential risks.