Local government debt of 36 Chinese cities hit 3.8 trillion yuan (HK$4.8 trillion) in 2012, up 13 percent from 2010, the National Audit Office.
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It warned some provincial capitals had used new loans to pay back old debts.
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Shanghai, Guangzhou, Chongqing and Tianjin are among the 36 cities mentioned in the audit report.
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About 16 cities have a gearing ratio of more than 100 percent, while the highest gearing hit 220 percent.
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The office warned some provincial capitals are facing high risks as their debt balances are growing too quickly.
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Five of these cities are covering 38 percent of their old debts with new loans, while 14 have a total overdue loan balance of 18.17 billion yuan.
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Debts have mainly arisen from expressway and other secondary highway projects, the report said.
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Bank loans and bonds were the main sources, accounting for 90 percent of the total debt raised.
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But NAO said some local governments were using unconventional ways to raise funds, posting new risks as the annual rate for these channels are as high as 18 percent.
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The report also pointed out local authorities had weak management over fund-raising platforms and debt control.
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Fitch downgraded China's local currency rating in April amid concerns over the country's rising local debt level.