That didn’t take long.

Just a few days after data showed that China’s banks were making new loans at a rate that would make a joke out of the government’s target of no more than $1.1 trillion in new loans in 2010, the country’s banking regulators are at work on a draft plan that would send capital ratios for China’s biggest banks to as high as 15% by the end of 2012, Bloomberg reported.

New bank loans soared to $80 billion in August. That was up from $78 billion in July and well above the $73 billion forecast by economists. To stay within the government’s lending targets for the year, banks would have to lend no more than $73 billion a month for the remainder of the year.

The draft plan, according to one of those unnamed but close to the regulators sources that are typically used to release trial balloons on new rules, would call for Tier One capital of 8%, an overall ratio of 10%, a buffer against economic cycles of an additional four percentage points, and a final one percentage point top-up for China’s most important banks.

That would be a potentially big increase from the current 11.5% ratio. (In contrast the proposed Basel III rule from global banking regulators would require a top 7.5% capital ratio.)

In 2009 China’s banks made a whopping $1.4 trillion in new loans, stoking fears for the health of the banking system and worries that all that lending would increase inflation and real estate speculation.

In an attempt to slow lending this year to “just” $1.1 trillion, Beijing has repeatedly raised reserve requirements for China’s banks. That has pushed banks into the financial markets to raise new capital. To date China’s banks have announced plans to raise $84 billion from the sale of stock in 2010. (Adding in the $22 billion raised in the Agricultural Bank of China initial public offering brings the total to $106 billion.)

The new rules, if enacted, would require banks to raise even more capital.

How much capital?

One estimate I’ve seen says that the full 3.5 percentage point increase would require banks to raise about $80 billion in additional capital. Even a two percentage point increase would require banks to raise 40% more capital than they’re planning to raise in 2010.

All this has renewed fears that growth in China is headed to a slowdown.  A slowdown wouldn’t bring growth to a standstill since China’s economy grew at an annual rate of 10.3% in the second quarter. The consensus among economists, according to a Bloomberg survey, is that growth will slow to 8.9% in 2011.

Many of the world’s countries, of course, would kill for 8.9% growth.