A Chinese restaurant owner allegedly laced his customers’ noodles with opium – to make sure they came back for more.

The restaurant owner – who goes by the name ‘Zhang’ – admitted to police in China’s northern Shaanxi province he had bought 4.4 lbs of poppy buds in August for £60, which he had ground into a powder before adding them to his noodles, according to the Hua Shang Bao daily.

‘Zhang’s’ actions were discovered only after customer Liu Juyou, 26, was pulled over by police during a routine traffic stop earlier this month and tested positive for opium.

Police did not believe Mr Joyou’s claims he had never taken drugs in his life and that he suspected the popular noodle shop was involved.

Mr Joyou managed to convince his family to eat the same noodles and test themselves for the drug, before presenting the positive results to police, who opened an investigation into the restaurant.

They discovered other customers were also unknowingly imbibing small amount of opium, which according to police, would gradually have built up to give a positive drugs test result.

An anti-narcotics police officer said to the South China Morning Post: “If the food is ingested over a long period of time, it would have an addictive effect”.

Mr Joyou, who was detained for 15 days, was released. However, despite finding the restaurant culpable, Mr Joyou’s appeal against his detention was dismissed by police, who said their priority was to detect drugs and punish drug users.