The country's top securities regulator is stepping up its efforts at cracking down on illegal activities involved in the recent stock market turmoil, particularly on stock-index futures trading, officials said on Friday.
China Securities Regulatory Commission has referred 22 cases of suspected market manipulation, insider trading, fabricating and spreading false information to the police, said Zhang Xiaojun, a commission spokesman.
The number of cases now under investigation has risen to 48 so far this year, he said.
Some listed companies and stock traders conspired to make up stories to drive up share prices, said Zhang, while others involved securities company employees taking advantage of their positions to trade stocks based on insider information.
"The illegal activities have earned billions in profits and seriously disrupted market order," said Zhang.
The China Financial Futures Exchange also announced on Friday that to clamp down on suspected market manipulation it had raised the nation's margin requirements on stock-index futures for the second time this week to 30 percent of the contract value on the CSI 500, SSE 50, and Shanghai-Shenzhen 300 indexes. It jumped to 20 percent on Aug 26.
The exchange also said it would view daily trading volumes of more than 100 contracts per account as "unusual transactions", and those will be subject to special supervision, a statement said.
Shanghai stocks closed 4.81 percent up on Friday, adding to Thursday's gain after the central bank said it was cutting interest rates and injecting liquidity into the market.
The benchmark Shanghai Composite Index climbed to 3,232.85 while the Shenzhen Component Index rose 5.32 percent to 10,800.
Sentiment rose among investors on speculation that China Securities Finance Corp Ltd would pour in 1.4 trillion yuan through inter-bank loans to stabilize the market. That would be the second rescue within two months, if it happened.
A more concrete signal came from the State Council, or the country's cabinet, which finalized guidelines on investments into the market by the country's huge pension fund, with up to 600 billion yuan from the fund likely to be injected into the market, it said.
Ren Zeping, chief economist at Guotai Junan Securities Co Ltd, said the stock market was heading into a "safety zone". "As regulations are tightened, the stock bubble will be further eliminated," said Ren.
After the monetary easing measures of recent weeks, the market is not short of funds, but lacks confidence, he said. "The central bank's easing may bring a rebound in the short term."