The China Consumers Association has criticized KFC, a leading chicken fast-food chain, for using a limited number of blind box sales to lure customers to over-purchase its food and cause food waste.

The association said on its website on Wednesday that such marketing can lead to impulsive and excessive consumption to obtain the limited edition blind boxes, which is "against public order and the spirit of the law".

The article was posted after KFC China collaborated with top domestic blind box toymaker Pop Mart to offer 260,000 dolls with its 99 yuan ($15.60) family-sized chicken bucket from Jan 4. The doll set features seven models of Dimoo, a popular character created by Pop Mart, with six regular ones and one hidden model, meaning customers have to pay at least 594 yuan to collect a complete set.

The sale sparked a frenzy on the internet.

By Friday, more than 85 percent of the toys had been sold across the nation, with remaining sales delayed in cities affected by the COVID-19 pandemic, Pop Mart said.

On Xianyu, a popular secondhand goods exchange platform, a set of six regular models is priced at around 700 yuan. Many users have also offered eating services for those who cannot finish the whole bucket, with prices ranging from 79 to 699 yuan.

The association said that to collect the whole set, customers need to buy at least six chicken buckets and the probability of obtaining the hidden model is 1 in 72. Some people have paid 10,494 yuan to buy 106 buckets and others have discarded the food they can't finish.

KFC's fast food has an expiry date and should be consumed in time and purchased on demand, the association said. The Anti-Food Waste Law adopted in April clearly stipulates that food operators should resist food waste, prompt customers to consume moderately and take measures to prevent waste rather than induce or mislead them to purchase excessively, it said.

The association also said that customers should consume "scientifically and rationally" and resist undesirable consumption behaviors.

Neither Pop Mart nor KFC China responded to requests for comment. KFC customer service said the dolls are still on sale and customers can consult local outlets for details.