A craze in which pupils use magnetic ball-bearings to mimic body piercings has left three children in hospital and is putting large numbers in danger, a surgeon has warned.
Sanja Besarovic said three children have been treated at Hull Royal Infirmary in the past three months after swallowing high powered ball-bearing magnets.
Ms Besarovic, known to the parents of seriously ill children in East Yorkshire as Miss B, said a four-year-old child was lucky to escape injury as the magnets stuck to each other and passed through the digestive system without complications.
But she said two others were admitted to the children's ward with significant internal damage.
One suffered a perforated stomach and duodenum after swallowing nine of the balls and another had a small bowel perforation.
Both underwent major surgery including a laparotomy and bowel resection.
Ms Besarovic, a consultant paediatric surgeon at Hull and East Yorkshire Hospitals NHS Trust, said she had written to the Royal Society for the Prevention of Accidents with her concerns.
She said: "We have been able to save these children but I'm growing increasingly concerned that this is happening more often.
"Both of the children recovered well after surgery but the next child may not be so lucky."
Ms Besarovic said: "We have seen three cases in the past three months alone and I am concerned about the growing incidence of this problem.
"Parents and schools should be aware of this craze so they can warn children of the life-threatening risks especially if swallowed at different times."
The surgeon said: "Most of the children are asymptomatic and first symptoms like abdominal pain, nausea, vomiting, develop only after damage had been done."
The trust believes youngsters are attempting to mimic tongue and cheek piercings, unaware that the magnets stick to each other through loops of gastrointestinal tract and could cause bowel perforation or intestinal blockage if they are swallowed.