Jiang said simulated trading in recent months had shown that investors are keen to be involved in the market.

Trading during the simulated trials was healthy and stable, Jiang said, and the debut of actual trading on Friday was also stable and healthy.

Trading of government bond futures will further help interest-rate liberalization and benefit China's financial markets in the long run, said Wang Wei, a researcher at the CFFEX, who was a director of the team that developed the bond futures.

The team that developed the contract paid great importance to risk controls, said Wang.

Improved risk controls for this new product will not allow any "abnormal" trading - such as the huge buy orders from Everbright Securities last month, said a spokesman at the CSRC on Friday.

"The China Financial Futures Exchange has taken measures to establish and supervise the futures margin system, and any transaction must have enough capital in the margin account" to ensure the trade will be completed, he said.

The new bond futures are mainly aimed at domestic financial institutions. Trading requires a minimum of 500,000 yuan in an investor's account. Foreign investors can't take part in the market directly, under CFFEX regulations.

The relaunch of bond futures contracts won't drain liquidity from the stock market, as the two markets focus on different investor categories.

"While retail investors are the major participants in the stock market, institutional investors dominate government bond futures trading. The debut of government bond futures had no obvious impact on Friday's stock market performance," said Gui Haoming, chief analyst of Shenyin Wanguo Securities Co.

Commercial banks are the largest holders of treasury bonds. As of the end of July, commercial banks held 5.146 trillion yuan in the bonds, or 68.9 percent of outstanding issues.

Commercial banks aren't allowed to trade treasury bond futures, under CFFEX regulations.

Chen Jia in Beijing contributed to this story.