BEIJING (BLOOMBERG) - China plans to raise retirement ages gradually over a number of years, instead of a drastic one-time change, a government researcher said last week, without providing any details on when the changes might start.

When the retirement age starts being lifted, it will be by a few months every year, or by a month every few months, according to Dr Jin Weigang, head of the Chinese Academy of Labour and Social Security under the Ministry of Human Resources and Social Security.

Dr Jin did not say when the changes would begin, but the current five-year plan calls for "raising the retirement age in a phased manner".

"People in different age groups will be retiring at different ages," Dr Jin said in an interview with state-run Xinhua news agency published on Saturday (March 13). "For example, in the first year of the policy's implementation, female workers who were originally scheduled to retire at 50 will retire one month or a few months after 50."

The policy should have a certain degree of flexibility to accommodate various kinds of workers' desires to retire at different ages, Dr Jin said. It will not be a "one-size-fits-all" plan and should leave room for individuals who wish to retire early, he said.

Dr Jin's comments give a rare glimpse into the official thinking behind the controversial proposal to postpone retirement, which was outlined in China's 14th five-year plan as an antidote to the rapidly ageing population and shrinking workforce. Male white-collar workers currently retire at 60 and females at 55, based on laws enacted in 1978.