With the growing popularity of "group purchasing", consumer complaints about the sector are also on the rise.

The Beijing Administration of Industry and Commerce said group purchase enterprises have become a hot subject for complaints. The administration said it received 21 complaints in August alone.

The complaints are mainly focused on discrepancies between goods or services consumers received and what was advertised on group purchase websites.

About 500 group purchase websites are located in Beijing and account for about half of the total number of such websites in China. To counter the problem of the rising number of complaints, the China International Electronic Commerce Center, which is under the Ministry of Commerce, said in early September that a quality certification and rating system will be put in place to regulate these websites.

But it's up to websites to decide whether they want to take part in the system or not, said Zhang Ge, a staff member at the center.

The idea of group purchase websites comes from the United States website Groupon.

Unlike other coupon websites, Groupon works using the group purchase method - if a lot of people sign up for a deal, the deal becomes available to all, if the predetermined minimum number is not met, no one gets the deal that day.

"I bought a meal through a group purchase website by paying only 10 percent of the original price," said Wen Jing, an avid group purchaser who uses the websites almost every day.

Many of the websites in Beijing focus on deals for food and drinks, hairdressing and entertainment.

It is difficult for consumers to ask for compensation if their interests are not met because they receive coupons and goods from two different parties, legal experts said.

Although consumers deal with websites directly, they receive the goods or services from others.

Qiu Baochang, director of the Consumer Rights Protection Committee within the Beijing Lawyers Association, said group purchase websites should bear some responsibility because they receive consumers' payments directly.