North Korean leader Kim Jong Un has sent "thanks" to officials and workers for their roles in developing the Wonsan-Kalma coastal tourist area, state-run media reported Monday, amid continued speculation that he is in poor health.

But the Korean Central News Agency did not elaborate on when that happened. Unless Kim, who has been absent from official media in over two weeks, actually makes an appearance, doubts about his health are unlikely to be dispelled, North Korea watchers say.

On Sunday, meanwhile, Moon Chung In, the top foreign policy adviser to South Korean President Moon Jae In, told U.S. media that Kim is well and has been staying since April 13 in the eastern port city of Wonsan, where his villa is situated.

Over the weekend, the U.S.-based website 38 North, which monitors North Korea, also said satellite imagery showed that a train probably belonging to Kim was spotted in Wonsan at least on Tuesday and Thursday.

Kim's movements have not been reported in the country's state-run media since April 12, when KCNA said he had presided over a meeting of the Political Bureau of the Central Committee of the ruling Workers' Party of Korea, held the day before.

Last week, CNN said the United States was monitoring intelligence that Kim was in grave danger after surgery, but Seoul claims that no unusual signs have been detected in Pyongyang and U.S. President Donald Trump has said he thinks "the report was incorrect."

On Saturday, Reuters reported China has sent medical experts to North Korea, citing three sources familiar with the situation, while the news agency said it was unable to determine what the dispatch of them indicated about the status of Kim's health.

In Beijing, Chinese Foreign Ministry spokesman Geng Shuang told reporters on Monday that there is no information China can provide.

In 2014, Kim was absent from public view for around 40 days, leading foreign affairs experts to believe that he was suffering health problems.