The nightmare scenario for China's leaders as they try to wean the country off a diet of easy credit and breakneck expansion is a local government buckling under the weight of its own debt. Few provinces fit that bill quite like Jiangsu, home to China's most indebted local government.
Hefty borrowings through banks, investment trusts and the bond market by Jiangsu's provincial, city and county governments have saddled the province north of Shanghai with debt far higher than its peers, public records show.
Many of the province's mainstay industries, including shipbuilding and the manufacturer of solar panels, are drowning in overcapacity. Profits are dwindling, and the government's tax growth is braking hard.
That leaves Jiangsu vulnerable as President Xi Jinping and Premier Li Keqiang slow the country's giant economy to push through reforms aimed at reducing its reliance on the massive investment that made the country the factory to the world in favor of more services- and consumption-led growth.
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As part of that, Beijing has ordered a clamp down on provincial government borrowing and land sales, the mainstay income for many local administrations. But equally, Beijing expects local governments to absorb much of the cost of downsizing many industries, leaving provinces like Jiangsu caught between a rock and a hard place.
Standard Chartered, Fitch and Credit Suisse have estimated local government debt in China at the equivalent of anywhere between 15 percent and 36 percent of the country's output, or as much as $3 trillion based on World Bank GDP figures for 2012.
"China's local government debt, if not better managed, can potentially pose a systemic and macro economic risk to the country," said Jun Ma, Deutsche Bank's greater China chief economist.
"This has historic precedents in Brazil where in the three crises of 1989, 1993 and 1999, the root cause was the state government's excess debt," he said.
Little public information is available on the total debt of Chinese local governments. Indeed, earlier this month China's Vice Finance Minister Zhu Guangyao said Beijing did not know the precise level of their debts either.
(Read more: Chinese officials even more pessimistic on local debt than Fitch)
But from what ratings agencies and think-tanks can piece together, Jiangsu may be the standout debt risk among China's 31 provinces.
Looking at bank loan books, they can see that China's eastern provinces including Jiangsu have the highest concentration of government debt. Jiangsu then looms large because of its reliance on costlier and alternative forms of financing, which they said suggested that cheaper bank loans and land sales are not giving the authorities the funding they need.
The risk that Jiangsu might pose to the Chinese economy in a crisis is clear. On its own, the province would be a top 20 global economy with GDP greater than G20 member Turkey. Its 79 million population tops that of most European countries.
Provincial government officials declined to comment for this story.