North Korean leader Kim Jong-un had surgery in Pyongyang in mid-September to treat fractures to both ankles and remains in hospital, a source claimed Monday.

The source, who recently visited the North, said, "I heard that Kim Jong-un injured his right ankle in June after pushing ahead with on-site visits and ended up fracturing both ankles because he left the injury unattended."

The source added Kim had surgery at the Bonghwa Clinic, an exclusive hospital for high-ranking party members, in mid-September and is now recovering there.

The source said bodyguards have been posted around the ward and security remains tight. "There's been a marked increase in the number of elite officials visiting the ward," the source added.

One intelligence official here said Kim's official car does not appear to have left Pyongyang, so it is likely he remains in the capital.

The official said Kim is overweight and appears to have sprained his ankles during a grueling tour of military bases and factories in Cuban heels. Kim is around 170 cm tall and has become noticeably overweight since he came to power.