Thinking that the eels would make him look ten years younger, Nan dived into the water and let them feast upon layers of dead skin.

But after laying in the spa bath, Nan felt a sharp pain and realised a small eel was working its way up his urethra and into his bladder.

'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.'

Rushing himself to hospital, the man underwent a three-hour operation to remove the six-inch eel which was dead by the time doctors found it.

Surgeon Jin Wang said that, because of the eel's slippery nature, it was able to make a smooth entry into the genitals of Nan.

'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.

— Metro