Courts have reported a sharp increase in customer protection cases brought by "professional" consumer rights activists.

In the past five years, almost half of the 661 cases concerning disputes over business contracts and product quality were instituted by familiar faces known for their campaigns against fake and shoddy goods, statistics from Shanghai's Huangpu District People's Court showed.

"Consumers trust them to institute legal proceedings after they find their rights have been infringed," said Jin Minzhen, vice-president of the court. "Sometimes these ‘professionals' buy products, which they know perfectly well are defective, and sue the retailers to claim compensation."

Last year more than 40 percent of cases in Chongqing involved a recognized consumer rights campaigner, according to Chongqing No 5 Intermediate People's Court.

In a case in Shanghai in October, a seasoned fighter against fake products and services sued a restaurant on behalf of a newly wed couple. The restaurant falsely advertised itself as a banquet hall to a four-star hotel on its wedding menu, according to court records. The defendant was judged to have committed fraud, and the "professional" campaigner helped the couple obtain their compensation.