SHANGHAI - Stocks on the Chinese mainland fell, capping the benchmark index's biggest weekly drop in two months, as a delayed debt-limit vote by US lawmakers fueled concerns over a possible default.

PetroChina Co led energy companies lower as oil futures headed for the first weekly drop in five weeks. China Railway Construction Corp fell to a record low after the 21st Century Business Herald said debt levels were forcing the railway ministry to withdraw from regional rail investments. China CITIC Bank Corp surged 7.8 percent, pacing gains for banks on speculation the central bank may cut reserve-requirement ratios.

The Shanghai Composite Index lost 7 points, or 0.3 percent, to 2701.73 at the 3 pm close. It slid 2.5 percent this week, the most since the period to May 27. The CSI 300 Index dropped 0.3 percent to 2972.08, taking its weekly loss to 3.1 percent.

"Debt risk is drawing most attention from investors at the moment," said Li Jun, a strategist at Central China Securities Co in Shanghai. "The uncertainty over the US debt default will keep hammering global stock markets until a deal is reached."

The stock market losses pared in the last hour of trade on speculation that the reserve-requirement ratio for lenders would be cut amid tight liquidity.

"It's pure rumor," said Lu Ting, a Hong Kong-based economist at Bank of America Merrill Lynch. The ratio was lifted to a record high of 21.5 percent last month, as the central bank ordered lenders to set aside more money after inflation reached a three-year high. An official from the news department of the People's Bank of China's declined to comment on the policy easing speculation.

Banks rally

A gauge of financial stocks in the CSI 300 Index climbed 1.8 percent, the most among 10 industry groups. China CITIC Bank surged 7.8 percent to 4.69 yuan (70 cents). China Vanke Co, the nation's biggest property developer, advanced 0.5 percent, pacing gains for real-estate companies.

Commodity Stocks

A gauge of materials in the CSI 300 Index retreated 1.8 percent, while one for and energy producers fell 1.7 percent, the most among industry groups. Oil futures fell as much as 0.5 percent in New York as concerns that a failure to reach a deal on the US debt limit countered signs that the economy is improving.

PetroChina, the largest oil producer, retreated 1 percent to 10.68 yuan. Shenhua Energy, the listed unit of the biggest coal producer, slid 2.3 percent to 29.69 yuan. Yanzhou Coal Mining Co sank 2.8 percent to 32.55 yuan. A drop in crude prices would curb demand for coal as an alternative source of energy.

Jiangxi Copper Co, the nation's biggest copper producer, slid 2.3 percent to 36.08 yuan.

China Railway Construction, builder of more than half of the nation's rail links since 1949, slid 1.5 percent to 5.27 yuan, the lowest price since the shares started trading in March 2008. CSR Corp, which made one of the trains involved in last week's train crash, fell 2 percent to 5.81 yuan.

China CNR Corp, the nation's second-biggest train maker, dropped 1.9 percent to 5.59 yuan. China CNR slumped 14 percent this week to Thursday.

Bloomberg News