Local governments across China have borrowed billions of dollars to build bridges, apartments and shopping malls, leaving many insolvent and endangering the country's financial system, analysts say.

While the central government in Beijing is in good financial shape -- it has a relatively small budget deficit, a huge trade surplus and the world's largest foreign exchange reserves -- it is a different picture outside the capital.

Local governments had borrowed 10.7 trillion yuan ($1.7 trillion) -- 27 percent of GDP -- by late 2010, according to official data, though ratings agency Moody's believes the figure is underestimated by 3.5 trillion yuan.

Several provinces have since published reports showing their debt-to-GDP ratio was higher than the national figure.

Moody's believes that between eight and 10 percent of loans made by Chinese banks will never be recouped.

"Debt across the board is rising very quickly," weakening the banking system, said Michael Pettis, a specialist in Chinese financial markets at Peking University.

"But any attempts to slow its growth results in a rapid reduction of investment and (economic) growth."

China's total public debt -- including the central and local governments -- stands at 68 percent of GDP, well below Italy's ratio of 120 percent or Japan's which stands at more than 200 percent.

But when it comes to local authorities the key concern is repayment.

To meet their commitments local governments need to generate income from land sales, which is fuelling unrest in the world's second largest economy as residents increasingly complain that land is being unlawfully seized.

Such corruption allegations have culminated in protests, such as the one in Wukan in the southern province of Guangdong last month, where villagers staged a revolt against authorities they said had been stealing their land for years.

Another source of income is from infrastructure projects, many of which are not profitable or legal.

Investment in highways, shopping malls and apartment buildings has been a key driver of the economy in recent years, especially since the 2008 global crisis when Beijing ordered banks to open the credit valves to spur activity.

"Over the past couple of years, more than half of Chinese GDP has been generated by investment in fixed assets" such as factories and roads, said Patrick Chovanec, an economics professor at Beijing's Tsinghua University.

There are "things that make economic sense but are not commercially viable" such as roads or hospitals which should have been funded by taxpayer money, he said.

An audit of local government debt in 2010 found that 530.9 billion yuan has been misused, including illegally diverted to property and the capital markets, and "fake" investments, the National Audit Office said last week.

Ultimately if the loans cannot be repaid, the banks will have to be bailed out by Beijing, meaning the central bank will have to print money, which will in turn create inflation -- already a major headache for policymakers.

A recent downturn in China's housing market will also weigh on the finances of cities and provinces that had planned to pay off debt by selling land at high prices.

With apartment prices beginning to fall, development plots are struggling to find buyers: in 2011, more than 900 sites offered to developers went unsold, compared with only 280 in 2010, the Beijing News said Friday.

Such sales represent a major share of municipalities' incomes -- 48 percent in the case of the southern city of Guangzhou in 2010, according to the China Business News.

In Shanghai, the country's economic capital, the average price per square metre paid by developers plummeted 41 percent last year, the same paper said.

As a result, the central government has sought to make local authority financing less dependent on real estate.

As an experiment, the rich coastal provinces of Guangdong and Zhejiang, along with the cities of Shanghai and Shenzhen, were authorised to issue bonds of their own in October for the first time in 17 years.

But the securities are low-yield and have so far mainly been sold to state commercial banks.

"If all goes smoothly, they (the banks) should be able to sell those bonds to other entities or individuals, said Ren Xianfang, senior analyst for IHS Global Insight in Beijing.

"If not, that's bad, as the very idea of such bond issues is to alleviate market concerns that the problem of banks' exposure to local debt has been resolved."

Nonetheless Lin Yifu, senior vice-president of the World Bank, told the China Daily last month that China was not at risk of a debt crisis like the one engulfing Europe.

"The government has much less debt than many developed countries, so any concern about a debt crisis in China is groundless," he said.