Zhou Ji, a 23-year-old associate in a leading auditing company, says he feels stressed whenever he thinks about covering most of his parents' expenses after they retire.

"Although my parents are both involved in the social security system, the pension they will get is simply not enough," Zhou says.

If Zhou, as an only child, marries a woman who is also an only child - which is likely - he will face the pressure of supporting four aged parents and at least one child. He dares not even think about getting married.

Zhou is one of the many young Chinese who feel "insecure" about China's social security system, especially the pension system.

With the increasing pressure of an aging population, many young Chinese who may have to support their parents in the future are questioning the pension system known for high premiums and low returns.

"My mother has already retired, and her pension is only 1,200 yuan (137 euros) a month. I cannot understand why she gets so little money after paying so many years into the pension fund," Zhou says.

Although the State Council announced a 10 percent rise (an average of 120 yuan) of the pension on Dec 22, retirees are still not satisfied in the face of high inflation.

An online survey conducted by ifeng.com, one of China's key portal websites, said 78.2 percent of the 100,745 participants thought the increase was not enough.

China's 230 million migrant workers - people who move from the countryside to work in cities - are also not included in the system.

Under the system, employers pay an equivalent of 20 percent of the employee's salary into the pension account, while the employee deposits 8 percent.

In the first 15 years of contributions, employees are able to collect only their contributions and do not have access to the money paid by employers, the major part of their pension.

By the end of 2009, China's pension accounts accounted for only 6.62 percent of the country's GDP. In many European countries, however, the figure is 40 to 50 percent, the National Business Daily reports.

It has been reported that the national pension account faced a 1.3 trillion yuan shortage at the end of 2010. With expansion of the system and inflation, the losses are expected to grow larger. By 2075, the shortage could grow to 9.15 trillion yuan, a World Bank report says.

The scheme in China is not run nationally, but rather by provincial or municipal governments. The result is that some governments in richer areas can balance their accounts after distribution, but some poorer ones have to be subsidized by the governments.

The imbalance of economic development between the east and west also makes the country unable to raise the pension standard.

A report of the Ministry of Human Resources and Social Security says 1.25 trillion yuan was saved in the pension account nationally in 2009, while local governments at all levels poured 164 billion yuan to local pension accounts in subsidies.

Meanwhile, the inability to widely invest the pension money is also hindering the growth of the fund.

A report of the National Audit Office shows that the return on investments of the pension fund is only 2 percent, lower than the CPI rise, which was 5.1 percent in November.

Qiu Yulin, professor of social security at Renmin University of China, says one main reason for the fund's low return is that it cannot be involved in the capital market.

Qiu says pension funds are allowed to invest in buying treasury bonds and depositing in banks, but both provide low returns.

The situation should ease once the fund is opened to the market, which some fund managers predict will be in three to five years.

China has issued licenses to 16 fund companies to manage its social security funds, but the pension fund is yet to be included.

Yue Jinglun, a social economics professor at Sun Yat-sen University in Guangzhou, says that to solve these problems, China needs to sort out how to invest pension funds with high returns and low risks, and how to supervise and guarantee that the funds are properly used.

If the problems cannot be effectively solved, the country will either need to charge more from employees, or raise the retirement age, he says.

Shanghai's municipal government has increased the retirement age from 55 to 60 for women, and from 60 to 65 for men.

"China's pension system is making efforts to improve," says Qiu, adding that it will take China a long time to catch up with the relatively advanced systems of European countries.

"The first pension regulation in Europe was released by Germany in 1889, but China waited until 1997 to have its actual pension system.

"The almost 100-year gap cannot be covered in a short time."