The forces of attraction proved too strong for an 11-year-old boy when the magnets he was playing with failed to detach from his penis, doctors report.

The child presented to Sakura Hospital in Chiba, Japan with penile pain and a crush injury to the foreskin.

Writing in Clinical Case Reports, doctors said the boy had been playing with neodymium magnets “in the bathroom out of curiosity”.

Neodymium magnets, also known as super magnets, are the strongest type of permanent magnets commercially available.