A slippery eel has slithered its way into a Chinese man's bladder through his penis during a cleansing spa.

The man, who was enjoying a relaxing skin treatment where live eels are used to help clean the body, felt a sharp pain and realised that one of the eels had snuck off into his body, the Metro reported.

"I climbed into the bath and I could feel the eels nibbling my body. But then suddenly I felt a severe pain and realised a small eel had gone into the end of my penis," the 56-year-old from Honghu, Hubei province said.

"I tried to hold it and take it out, but the eel was too slippery to be held and it disappeared up my penis."

The man was rushed to hospital, where the eel was removed from his body after a three-hour operation.

The slithering nature of the eel gave it the perfect ability to slip into the man's body through his genitals, surgeon Jin Wang said.

"The diameter of the urethra in a man's penis is just a little narrower, but because eels are quite slippery, its body worked as a lubricant and so it got into the penis smoothly," he said.

Unfortunately for the eel, its journey did not end well with the surgeons finding the critter dead in the man's bladder.