WAHSINGTON -- US Secretary of State Mike Pompeo said Wednesday that the United States is watching closely what's happening inside North Korea amid reports that its leader Kim Jong-un is seriously ill, but gave no other details.

"As the president said last evening ... we're watching closely what's taking place there, but I don't have anything to add," he said during a press briefing.

President Donald Trump told reporters Tuesday that the US doesn't know about Kim's health condition. He said he wishes the North Korean leader well.

The remarks follow a CNN report Monday that cited an unidentified US official as saying that the US is looking into intelligence that Kim is in "grave danger" after a surgery.

An earlier report by the Daily NK, a South Korean internet news outlet specializing in North Korea news, said Kim has been receiving medical treatment following a cardiovascular procedure.

South Korean officials dismissed the reports, saying no unusual signs have been detected in the North to suggest that something may be wrong with the leader's health.

US Joint Chiefs of Staff Vice Chairman Gen. John Hyten also said Wednesday that he has no information about Kim's condition.

"I can tell you that in the intel, I don't have anything to confirm or deny anything along those lines," he said during a Pentagon press briefing. "So I assume that Kim Jong-un is still in full control of the Korean nuclear forces and the Korean military forces. I have no reason not to assume that."

Speculation about Kim's whereabouts started after he apparently skipped an annual visit to the Kumsusan Palace of the Sun last Wednesday on the occasion of the 108th birthday of his late grandfather and state founder, Kim Il-sung.

Kim was last seen April 11 in state media reports about his presiding over a political bureau meeting of the ruling Workers' Party, where he called for "strict national countermeasures to thoroughly check the infiltration of the virus." (Yonhap)