Shanghai will begin testing a flexible retirement system on Oct.9 amid rising fears that the country's expanding aging population would leave heavy pressure on the national social security and pension systems.

The tentative measure will give the citizens the option of postponing retirement and apply only to enterprise workers, while civil servants and those working for the government-sponored undertakings will still follow the current system which was stipulated by Chinese laws.

Under the new terms, eligible employees are permitted to postpone retirement until 65 for men and 60 for women. The current retirement age in China is 60 for men, 55 for female cadres and 50 for women workers.

"The system tries to be applicable to all needs of the residents - Those who want to retire on schedule can do so, while those who wish to continue working may also do so," says Bao Danru, deputy director of the Shanghai Bureau of Social Security.

Debates over whether the pushback of the retirement age is efficient to ease the pressure on the insufficient pension funds have become fierce recently.

According to Zheng Bingwen, from the Chinese Academy of Social Sciences, China's pension deficit has topped 1.3 trillion yuan ($200 billion) and will enlarge in the future.

However Lu Guoping, a columnist for some domesitc media outlets, pointed out that the postponement could not cut the deficit, but only delay its impacts. He also worried the longer working years of employees, especially those in senior posts, may leave fewer opportunities for youngsters.

In September, China's Ministry of Human Resources and Social Security said it would not adjust the retirement age nationwide any time in the near future.