* HSI -1.0 pct, H-shares -0.8 pct, CSI300 -0.5 pct
* Hong Kong shares heading for worst week since May 2012
* New World Development falls to 21-month low after rights issue
By Alice Woodhouse and Chen Yixin
HONG KONG/SHANGHAI, Mar 14 (Reuters) - Hong Kong shares fell on Friday, dragged down by index heavyweight Tencent Holdings Ltd after the Chinese central bank called for a halt to certain types of mobile payments, causing a slide in online-payment-related stocks in China.
China shares dropped and hovered around two-month lows as nerves over the latest economic data stoked concerns of a slowing Chinese economy.
By midday, the Hang Seng Index was down 1 percent at 21,541.04 points. On the week, it has fallen 4.9 percent and is heading for its largest weekly loss since May 2012.
The China Enterprises Index of the top Chinese listings in Hong Kong dropped 0.8 percent and has fallen 4.7 percent for the week, its largest weekly loss since June 2013.
The CSI300 index of the largest Shanghai and Shenzhen A-share listings fell 0.5 percent, while the Shanghai Composite Index was down 0.5 percent at 2,008.36 points. On the week, they have fallen 1.7 percent and 2.4 percent, respectively.
Tencent Holdings Ltd dropped as much as 6.4 percent to its lowest in four weeks, after the People's Bank of China demanded that payments made by scanning a bar code with mobile devices be halted, amid concerns over the security of their verification procedures.
Tencent, China's largest listed Internet company, and e-commerce firm Alibaba confirmed to Reuters that they had received a notice from the PBOC about the move.
"Tencent itself is a news-driven stock and people got used to seeing the shares jump lately due to its frequent expansion moves. Investors were nervous because of the report and locked in profit after the recent rally, in particular ahead of its earnings next week," said Ben Kwong, chief operating officer at KGI Asia.
"The market is cautious and people are nervous after the latest set of China data which confirmed a slowing economy in the mainland," Kwong said.
China Citic Bank , which earlier this week said it had teamed up with Tencent and Alibaba (China) on Internet finance services, fell 8.1 percent in Shanghai and 6.9 percent in Hong Kong.
Quick response (QR) codes companies, the technology used for mobile online payments, were among the top drags in the market. Fujian Newland Computer Co Ltd dived 8.9 percent, while SZZT Electronics Co Ltd lost 7.3 percent.
Shares in Hong Kong property developer New World Development Co Ltd fell 14.8 percent to its lowest since June 2012, after it announced on Friday a rights issue plan and said it would take its majority-owned New World China Land private for HK$18.6 billion ($2.4 billion).
Shares in New World China Land Ltd jumped 28.8 percent.