On Tuesday, Chinese and South Korean officials have cast doubt on claims that North Korean leader Kim Jong Un was sick following media reports that he had undergone a cardiovascular operation and was in "extreme danger."

Daily NK, a speciality website based in South Korea, on Monday reported, citing an unidentified source in Pyongyan, that Kim was recovering after the operation on April 12. Kim is estimated to be around 36 years old.

Mystery hung in the air as to the real physical condition of the North Korean leader after US and South Korean officials issued contradictory accounts following his absence from the country's recent holiday festivities.

Since having cardiovascular surgery last week, Kim was said to be in critical condition and the Trump administration was not certain about his health status, U.S. officials, who requested anonymity, divulged.

One of the officials said the White House was told that after the operation, Kim took a turn for the worse, although CNN earlier quoted a U.S. official with direct knowledge suggesting the young dictator could be in "serious danger."

A report by the Daily NK claimed that an unnamed source said Kim was recovering in a villa in the eastern part of North Korea. Officials from the White House did not immediately confirm the report.

A South Korean official stated there was "nothing special" in terms of proof to verify the claims, the South Korean news outlet Yonhap News, said. The official added that not long ago, Kim continued to participate in public activities. A Chinese official who deals with North Korean affairs also disclosed to Reuters that Kim is not believed to be seriously ill.

Chinese foreign ministry spokesperson Geng Shuang said that Beijing was aware of claims about the physical condition of the North Korean dictator, but added they have no information about the source, without giving out any further comments on whether it has any knowledge about the situation.

Meanwhile, South Korean stocks exposed to North Korea fell and the Korean currency dropped on the latest reports. The won was trading down, over 1 percent against the US greenback even as the South Korean government sources disclosed Kim was not seriously sick.

News surrounding Kim's physical well-being triggered the benchmark Kospi to stretch losses to as much as 3 percent. The Kospi settled 1 percent lower.

Any leadership crisis in the hermit state could potentially have a serious impact for regional stability, including talks with the U.S. over Pyongyang's nuclear stockpile.