(Corrects last paragraph to say 3SBio Inc and WuXi Biologics were HK's biggest biotech IPOs, not China Resources Pharma Group)
* First float under new Hong Kong rules for biotechs
* Shares rise as much as 6.4 percent in initial trade
* At least 10 more biotechs planning HK listings this year
By Julia Fioretti and Kane Wu
HONG KONG, Aug 1 (Reuters) - Shares in Chinese biotech company Ascletis Pharma Inc rose as much as 6.4 percent on their debut in Hong Kong on Wednesday, in the first such listing in the city under new rules designed to attract drug developers.
The initial public offering (IPO) is seen as a test of the new regime as Hong Kong seeks to establish itself as a financing centre for the growing number of Chinese biotechs. A successful float by Ascletis is thought likely to encourage fellow biotechs to pursue a listing.
The rules are part of the city's efforts to better compete against New York, its arch rival, for listings. Currently the U.S. is the biggest centre for biotech IPOs, with $2.4 billion worth of such shares sold last year.
Ascletis shares rose as high as HK$14.9 as trading got underway, compared with the IPO price of HK$14. However they eased to HK$14 after the first hour of trade in a flat market.
Ascletis last month priced its deal at the middle of a HK$12 to HK$16 range, valuing the biotech firm at $2 billion.
Under rules in place since April 30, biotech firms without revenue or profit can apply to list in Hong Kong.
More than 10 companies - mostly Chinese and including Innovent Biologics and Shanghai Henlius Biotech - plan to list in Hong Kong and some have dropped U.S. IPO plans in favour of listing closer to home.
Ascletis sold 224 million new shares, or 20 percent of its enlarged share capital, in the IPO.
Responding to questions about China's recent vaccine scandal, where a pharmaceutical company was found to have made and distributed poor quality vaccines, Ascletis founder Wu Jinzi said quality was "the lifeline" of his company.
"We are going to make the best quality, most effective and the safest drugs for patients in China and the world," Wu said at the listing ceremony at the Hong Kong exchange.
Hangzhou-based Ascletis, founded in 2013, has two hepatitis C virus drug candidates at or near commercial stage and one HIV drug that has completed a phase IIa clinical trial. It also has a liver cancer drug candidate that has completed phase I and phase I extension clinical trials.
China Merchants Securities, Goldman Sachs and Morgan Stanley led the deal.
The biggest biotech IPOs in Hong Kong - under previous rules which required certain levels of either profitability or cashflow - were that of 3SBio Inc and WuXi Biologics which raised $818 million in 2015 and $587 million last year, respectively.
Reporting by Julia Fioretti and Kane Wu; Editing by Christopher Cushing and Stephen Coates