The Washington Post said Friday citing two sources familiar with the situation that South Korean and U.S. authorities believe North Korean leader Kim Jong-un retreated to the coastal town of Wonsan after becoming aware in mid-April that subordinates in his vicinity had suffered from a fever. 

North Korean media on Saturday reported on Kim's public appearance following his 20-day absence since April 11, which sparked wild speculations on his health and whereabouts.

The Post said intelligence officials in Seoul and Washington believe dozens of North Korean residents in the border area with China have been quarantined in response to COVID-19, while the regime continues to publicly claim it has no reported cases of the disease in the country.

The report said Kim's unexplained disappearance may have been an effort to avoid having to acknowledge coronavirus concerns involving his subordinates.