China's tumbling stock market showed signs of seizing up today as the dramatic sell-off continued despite efforts by regulators to try to stem the losses. The CS I300 index of the largest listed companies in Shanghai and Shenzhen closed 6.8 percent down, while the Shanghai Composite Index dropped 5.9 percent after losing more than eight per cent at one point. Companies scrambled to escape the rout by having their shares suspended and indexes plunged after the securities regulator warned of panic sentiment gripping investors. The losses come despite Chinese leaders announcing fresh measures to deal with a correction that has wiped trillions off the country's markets. Beijing unveiled yet another battery of measures to arrest the sell-off, and the People's Bank of China said it would step up support to brokerages enlisted to prop up shares. More than 30 percent has been knocked off the value of Chinese shares since mid-June, and for some global investors the fear that China's market turmoil will destabilize the real economy is now a bigger risk than the crisis in Greece. Most other regional markets were also hit by the spillover effects, with many hosting companies with links to China. Tokyo sank 3.14 per cent, Seoul slipped 1.18 per cent, Sydney retreated 2.01 percent while Taipei shed 2.96 per cent.