A mystery needle found in the lung of a former South Korean president has sparked a controversy involving a famed acupuncturist and the country's 20,000 oriental medicine doctors.

The seven-centimetre (2.75 inch) needle was discovered last month by doctors who examined Roh Tae-Woo for violent coughing.

It was later surgically removed and doctors reported no serious health setbacks for the 78-year-old former general, who ruled from 1988 to 1993.

But the Association of Korean Oriental Medicine has urged prosecutors to investigate the case, saying its members were not involved but an unlicensed acupuncturist may have been.

"It is impossible for an officially-trained doctor to perform a treatment that can send a needle all the way down to the lung," the association spokeswoman told AFP.

"We want the truth about this incident to become known by the public. Whoever did this should be punished for sparking public distrust of our profession."

A media report said the needle came from an unlicensed acupuncturist trained under Kim Nam-Soo, 96. Despite Kim's celebrity as an acupuncturist, the association does not consider him a licensed practitioner.

Kim, quoted by Thursday's Korea Times, said he had not personally performed acupuncture on Roh since 1993.

However, he did not rule out the involvement of one of his numerous apprentices and urged Roh himself to reveal the truth.