Shanghai stocks closed down 4.27 percent on Friday after a gauge of manufacturing activity tumbled to its lowest in more than six years, showing more weakness in the world's second-largest economy, dealers said.

China's benchmark Shanghai Composite Index plunged 156.55 points to 3,507.74 on turnover of 450.6 billion yuan ($70.6 billion), but managed to end just above the key 3,500 point level.

The Shenzhen Composite Index, which tracks stocks on China's second exchange, slumped 5.39 percent, or 116.09 points, to 2,039.40 on turnover of 418.8 billion yuan.