China's 12 joint-stock commercial banks posted net profit of 45.2 billion yuan ($6.6 billion) in the first half of this year, down 19.3 percent from a year earlier, the official Xinhua news agency reported on Saturday, quoting a banking regulatory official.

Net profit fell as China's loose monetary policy cut interest rate earnings, Xiao Yuanqi, a director at the China Banking Regulatory Commission (CBRC), was quoted as saying. Revenue on intermediary businesses also declined due to the economic slowdown, he said.

Margins on interest rates fell 81 basis points in the first half, Xiao said on Friday.

He added there were signs of rising non-performing loans at these banks and bad debt may rise sharply in two or three years.

The joint-stock banks include CITIC Bank, China Merchants Bank, Minsheng Banking Corp, Huaxia Bank, Shanghai Pudong Development Bank, China Everbright Bank, Shenzhen Development Bank, Guangdong Development Bank, Industrial Bank, Evergrowing Bank, China Zheshang Bank, and China Bohai Bank.

Xiao said asset quality was at risk of deteriorating because of a surge in new lending in the first six months, which hit 7.37 trillion yuan, as the government put into place moderately easy monetary policy to boost the economy.

CBRC Chairman Liu Mingkang also urged the joint-stock commercial banks at a meeting on Friday to bolster risk management and closely monitor the flow of capital to prevent credit risk.

Worries about a further clamping down in lending spurred a pullback of the Chinese stock market, which posted its biggest weekly drop this week in five months.

($1=6.834 Yuan)

 (Reporting by Jacqueline Wong; Editing by Bill Tarrant)