North Korean leader Kim Jong-un has had surgery to remove a cyst from his ankle, according to South Korean intelligence.
A spy agency briefing to lawmakers on Tuesday said that a foreign doctor operated on Mr Kim in September or October.
Mr Kim recently dropped out of public view for nearly six weeks leading to speculation that he was seriously ill.
He has been seen walking with a stick in recent official photographs.
One such photo, used by North Korean media, showed him using a stick on 14 October as he inspected a new residential district.
Mr Kim had not been seen since September. South Korean intelligence says the cyst could recur because the North Korean leader is a smoker and leads a busy lifestyle.
South Korean politicians were told that foreign medical experts had been flown to the North Korean capital, Pyongyang, to remove the cyst from Mr Kim's left ankle.
The growth which materialised in May was caused by what is known as "tarsal tunnel syndrome" whereby a nerve is pinched, causing the ankle to swell.
An intelligence official said the medical team was from Europe but did not specify which country.
This is not the first time that a North Korean leader has been treated by foreign experts.
Kim Jong-un's father and grandfather were reported to have been treated by French doctors during their leaderships.
It was reported that a pace-maker was flown out from Switzerland in a diplomatic bag for Kim Il-sung, the founder of North Korea.
On 28 October, North Korean officials also attended talks with Japan for the first time in a decade to discuss the abduction of Japanese citizens.
North Korea has admitted it kidnapped 13 Japanese citizens in the 1970s and 80s to train spies in Japanese customs.
Five of them were returned to Japan in 2002. Pyongyang says the other eight died but Japan has said it does not believe this.
Japan lifted some sanctions on Pyongyang in July in return for North Korea's agreement to reopen an investigation into the fates of Japanese abductees.