UPDATE 1-New listings zoom on debut as China resumes IPOs

* New listings more than double as China resumes IPOs

* Exchange implements circuit-breaker rules to halt trade

* Good omen for coming IPOs, risks for existing investors

By Lu Jianxin and Doug Young

SHANGHAI/HONG KONG, July 10 (Reuters) - Shares in China's first initial public offerings in 10 months more than doubled in their debut on Friday, boding well for coming IPOs even as a flood of new offerings poses risks for existing investors.

Shenzhen-listed A shares in Guilin Sanjin Pharmaceutical Co (002275.SZ), a traditional Chinese medicine maker, kicked off trading at 32.50 yuan from their IPO price of 19.80 yuan and jumped as high as 39 yuan in early trade.

Shares of industrial cable maker Zhejiang Wanma (002276.SZ) opened at 22.50 yuan, nearly double their IPO price of 11.50 yuan, and climbed as high as 27 yuan.

Their prices fell off the highs after the Shenzhen Stock Exchange exercised new circuit-breaker rules for newly listed shares, suspending trading for 30 minutes after they rose 20 percent in intraday trading.

"Such strong debuts will be very encouraging for future IPOs," said Zhou Lin, senior analyst at Huatai Securities in Nanjing. "But I simply don't understand how investors can ignore risks by trading at such high valuations. There have been so many cases of huge losses by speculating in new shares."

A Reuters survey of six analysts and fund managers on Thursday had predicted the massive rises, forecasting the shares would jump as much as 100 percent from their IPO prices.

While impressive by global standards, such strong gains are not unusual for Chinese firms, especially small caps with a limited number of shares offered and following the recent pause in listings that began at the height of the global crisis last year.

In other China-related IPO news, shares of Amber Energy (0090.HK) zoomed on their trading debut in Hong Kong, climbing to HK$2.98 versus an IPO price of HK$1.66. [ID:nHKG249027]

STRONG PIPELINE

Around 30 firms have won initial approval but have been waiting for up to a year to go public in China after a slumping market led the stock regulator to quietly suspend new offerings last autumn as global stock markets tanked.

Hong Kong-listed toll road operator Sichuan Expressway Co (0107.HK) said on Monday it planned to raise up to 2 billion yuan ($293 million) in a public sale of new shares on the Shanghai Stock Exchange in mid-July to become China's first major IPO since last September.

State media also said this week that China State Construction Engineering Corp, the country's largest homebuilder, would raise as much as 42.6 billion yuan in a Shanghai IPO next month.