More than 10,000 dogs are reportedly slaughtered during the festival. The meat is traditionally associated with promoting heat and virility.

The groups also say that, according to data from 28 provinces across the country, the industry sources meat from strays and pets, which have been abducted.

Chen Minjie, of the Hong Kong-based Animals Asia Foundation, said: "We want the government to verify the source of all dog meat and crack down on the stealing of pets.

"Food safety is becoming more of an issue in China. We would like them to turn their attention to dog meat.

"Some of them are pedigrees, many wear collars and are ear-tagged, so it's obvious they are people's pets," she added.

Du Yufeng , an activist with animal protection NGO Boai, who co-ordinates protests at the festival, said: "People from all over the country return home for the festival. It's an important time of year for Yulin people, like Christmas in the West."

She said she routinely received reports of stolen pets in the lead-up to the festival.

Chen said live dogs were reportedly trucked in from around the country over long distances, which could also result in widespread disease, including rabies.

"The dog meat is not quarantined and the dogs' origins are unknown, so there are problems of food safety," she said.

On the day of the festival on June 21, an official response from the Yulin local government, said: "The government does not organise or advocate the festival … Currently, the legislation regarding animal hygiene and quarantine is quite perfect."