China stocks jumped on Wednesday, with Shanghai Composite index marking the biggest daily gain in 10 weeks, as the country's securities regulator assuaged concerns over new delisting rules and calmed investors following a sell-off in small-cap shares.

Hong Kong stocks turned positive at the close.

The China Securities Regulatory Commission (CSRC) said late Tuesday that tighter rules would not spark a wave of delistings.

The regulator also refuted the view that latest delisting rules would hit small caps, saying that only about 30 companies would be delisted next year under the new regulation.

China's small-cap CSI 2000 INDEX surged 6.7% to lead the gains.

UBS, meanwhile, upgraded 2024 real GDP growth forecast on Wednesday for China to 4.9% from 4.6%, due to improved first-quarter economic data and stronger export outlook.

** At the close, the Shanghai Composite index was up 2.14% at 3,071.38.

** The blue-chip CSI300 index was up 1.5%, with its financial sector sub-index higher by 1.7%, the consumer staples sector up 0.05%, the real estate index up 1.1% and the healthcare sub-index up 1.6%.

** The smaller Shenzhen index ended 3.8% higher and the start-up board ChiNext Composite index closed 2.1% stronger.

** Around the region, MSCI's Asia ex-Japan stock index was firmer by 0.3%, while Japan's Nikkei index closed down 1.3%.

** At 0811 GMT, the yuan was quoted at 7.2373 per U.S. dollar, 0.01% firmer than the previous close of 7.238.

** At the close of trade, the Hang Seng index was up 2.87 points or 0.02% at 16,251.84. The Hang Seng China Enterprises index rose 0.1% to 5,749.69.

** The sub-index of the Hang Seng tracking energy shares dipped 0.8%, while the IT sector dipped 0.31%, the financial sector ended 0.43% higher and the property sector dipped 0.3%.

(Reporting by Summer Zhen; Editing by Rashmi Aich and Sherry Jacob-Phillips)