South Korea plays down report on health of N.Korea's Kim Jong-Un

South Korea played down a report Tuesday that the North’s leader Kim Jong Un was being treated after surgery, as speculation mounted over his absence from a key anniversary.

Pyongyang marked the birthday of its late founder, Kim’s grandfather Kim Il Sung, on April 15 — by far the most important date in its annual political calendar — but Kim was not seen in attendance.

Daily NK, an online media outlet run mostly by North Korean defectors, said Kim had undergone a cardiovascular procedure earlier this month and was recovering at a villa in North Phyongan province.

“Excessive smoking, obesity, and fatigue were the direct causes of Kim’s urgent cardiovascular treatment,” it cited an unidentified source inside the country as saying.

No confirmation of the report was immediately available.

But it triggered widespread speculation, with CNN citing a US official saying that Washington was “monitoring intelligence” that Kim was in “grave danger” after undergoing surgery.

In a statement, a spokesman for the South’s presidential Blue House said: “We have nothing to confirm and no special movement has been detected inside North Korea as of now.”

The South’s Yonhap news agency, meanwhile, cited an unnamed government official saying that reports Kim was seriously ill were “not true”.

But there were no explicit denials that Kim, who is in his mid-30s, had had some kind of procedure.

Previous absences from the public eye on Kim’s part have prompted speculation about his health.

In 2014 he dropped out of sight for nearly six weeks before reappearing with a cane. Days later, the South’s spy agency said he had undergone surgery to remove a cyst from his ankle.

“Kim Jong Il had been dead several days before it was announced and it took everyone by surprise,” he tweeted.