SHIJIAZHUANG, Jan. 8 (Xinhua) -- Hejian, a city in northern China famed for its donkey burgers, has vowed to punish fake meat producers following media reports.

Chinese media reported that some butchers in Hejian, in northern China's Hebei province, used mule, horse and pig meat and sold them as donkey meat, mostly to restaurants in Beijing, reports said.

Hejian government called an emergency meeting on Monday and began an investigation.

Donkey burger is a famous delicacy in northern China, dating back several hundred years.