Chinese stocks closed mixed on Tuesday with the benchmark Shanghai Composite Index gaining the most in three weeks, driven by rallies among steelmakers and oil refiners.

The benchmark Shanghai Composite Index rose 0.85 percent, or 17.45 points, to close at 2,073.15. The Shenzhen Component Index closed at 8,400.36, down 0.02 percent, or 1.79 points.[Businesses Registration]

Combined turnover on the two bourses shrank to 92.33 billion yuan (14.56 billion U.S. dollars) from 102.7 billion yuan the previous day.

Gainers outnumbered losers by 707 to 221 in Shanghai and by 1,127 to 343 in Shenzhen.

Heavyweight sectors lead the afternoon gains after hitting a 41-month low on Monday, prompting investors to wonder whether the market has hit a turning point.

Baoshan Iron & Steel (BaoSteel), China's biggest listed steelmaker, unveiled plans to buy back up to 5 billion yuan of its total shares to boost investor confidence.

BaoSteel rose by the 10 percent daily limit to close at 4.48 yuan per share on Tuesday.

Oil refiners also gained momentum, encouraged by speculation that more listed companies will buy back their shares, especially heavyweights whose market prices are below book value.[Hong Kong Company Formation & Registration]

Sinopec, the country's largest oil refiner, jumped 5.41 percent to close at 6.23 yuan per share Tuesday.

In addition, the market was shored up by China Securities Finance Company's release of securities financing rules on Tuesday, which is expected to generate capital flow of 120 billion yuan.