* China shares drop to 4-week low as loan data worries
* HSBC, China Mobile tank in HK as investors turn wary
* Metal stocks slide as commodity prices weaken (Updates to mid-morning)
By Parvathy Ullatil and Claire Zhang
HONG KONG, Aug 12 (Reuters) - Chinese stocks sank to a four-week low on Wednesday morning on broad-based selling as worries deepened about a possible tightening of market liquidity after a sharp drop in bank lending in July.
Hong Kong shares followed suit, with overnight losses on Wall Street and the slide in Shanghai stocks, giving investors the excuse they needed to take profit on the recent rally that took the main index to a near 12-month high.
"The rally in the (Shanghai) index has far exceeded the speed of economic recovery," said Western Securities analyst Cao Xuefeng. "Yesterday's mixed economic data and sharp drop in bank lending heightened such worries, while weak overseas markets triggered the sell-off."
China's central bank said on Tuesday that banks extended 355.9 billion yuan ($52.08 billion) in new local-currency loans in July, down from 1.53 trillion yuan in June and a sharper fall than many analysts had forecast, although the second half had been widely expected to see a marked slowdown in lending.
By 0400 GMT, the benchmark Hang Seng Index was 2.3 percent lower at 20,588.90 with HK$33.6 billion shares changing hands. Analyst see the index supported at around 20,000 points in the near term, close to its 20-day moving average.
Index heavyweights HSBC and China Mobile both of which surged in recent sessions on mounting speculation on an impending Shanghai listing for the two stocks.
The HSBC stock was down 3.7 percent, while shares in the world's largest wireless network operator dropped 3 percent.
"Yesterday's data has made investors fearful again about the pace of the recovery in China. The low turnover in the recent rebound indicates that investors are wary of a correction happening soon," said Castor Pang, strategist with Sun Hung Kai Financial
Investors were cautious ahead of the outcome of the two-day U.S. Federal Reserve meeting, which is expected to provide hints on how the recovery in the world's largest economy will progress.
The China Enterprises Index, which represents top locally listed mainland Chinese stocks, was down 2 percent at 11,748.56 with PetroChina down 3.5 percent as weak oil prices weighed.
Bucking the trend, Brightoil Petroleum jumped 12.2 percent after the company said it would team up with a Chinese partner for a $1.05 billion oil pipeline connecting planned oil storage facilities in Dalian City with the national oil pipelines.
The Shanghai Composite Index ended the morning down 2.4 percent at 3,186.129 points, after fallings as far as 3.1 percent to 3,163.697 points late in the morning session.
Losing Shanghai A shares outnumbered gainers by 772 to 162, while turnover for Shanghai A shares edged up to 79.7 billion yuan ($11.7 billion) from Tuesday's morning's 77.6 billion yuan.
Analysts said weakness in overseas markets spurred the fall after Tuesday's modestly higher close, while shrinking turnover in recent days showed waning investor confidence after the index surged more than 90 percent since the start of the year, peaking last week at a 14-month high.
Metal, steel and coal shares were weak, with Jiangxi Copper dropping 5.7 percent to 40.10 yuan, Baoshan Steeel lost 4.5 percent to 8.50 yuan while China Shenhua Energy slid 3.6 percent to 35.75 yuan. (Editing by Edmund Klamann and Chris Lewis)