The number of Chinese Internet users hit 485 million at the end of June, with microblogging and group-buying posting the highest user growth rates, a Chinese government Internet statistical body said on Tuesday.

The number of microblogging or Weibo users rose over 200 percent in the first six months of the year to 195 million users from 63.1 million at the end of 2010, said the China Internet Network Information Center in a report.

The number of group-buying users also rose 125 percent to 42.2 million users from 18.7 million users at the end of 2010.

Sina Corp, Tencent Holdings and Baidu compete in China's hot Weibo space. Weibo acts like Twitter by allowing users to post links and short messages and accrue followers. Twitter, Facebook and YouTube are blocked in China.

The rise in the number of Weibo users could be causing a knock-on effect on the more traditional social-networking sites that saw the number of users fall to 230 million in the first half of the year from 235.1 million at the end of last year.

Renren Inc, Tencent and Kaixin001 compete in the traditional SNS space.

Despite the rise in total number of Web users, China's Internet penetration rate remains low -- at around 36 percent -- compared with developed Asian countries South Korea and Japan, which boast Internet penetration rates of more than 70 percent.

There are also signs that China's Internet growth is slowing, CNNIC's data showed. The rise of 6.1 percent over the end of 2010 is the slowest annual growth rate recorded.

(Reporting by Melanie Lee; Editing by Ken Wills)