South Korean officials today called for caution amid reports that North Korean leader Kim Yong Un might be ill, and Moon Chung National Security Adviser told the South Korean president that Kim is "alive and well."

South Korean Unification Minister Kim Yoon Chul, who is in charge of communicating with North Korea, said at a forum organized behind closed doors on Sunday that the intelligence data available to his government indicates that there is nothing unusual in the northern neighbor.

Moon Ji, the national security adviser to the South Korean President, told CNN that the Seoul government’s position is firm, that the North Korean leader is still alive and in good health, adding that Kim Young-un has been in the Winson region since April 13. And that his country's authorities have not detected any suspicious movements so far in the northern neighbor.

The source of speculation
There was speculation about the health of Kim Yong Un after his absence from the ceremony marking the birthday of his grandfather, Kim Il Sung - founder of North Korea - on April 15, and did not appear publicly after that date.

Kim last appeared on April 11 during a meeting of the ruling party's political bureau, and then on an inspection tour of an air base that was reported by official media on the 12th of the same month.

Yesterday, the Washington-based "38 North" Research Center for North Korea Affairs, published satellite images, showed it showed a special train likely to belong to the North Korean leader at a resort in the country this week, amid conflicting reports about Kim's health and location, some of whom talked about Kim's operation Surgical.

Satellite image reviewed by "38 North" center, showing a train that the North Korean leader is likely to be stopped at a resort in the north of the country (Reuters)

The "Daily in Kai" website, which is run by opposition North Koreans, has stated that the North Korean leader underwent surgery this month due to his suffering from problems in the arteries of the heart, and that he is going through a recovery period in Pune Gan Province in the north.

In contrast, the official North Korean media today did not display any new photos of Kim, and did not mention his whereabouts, but published reports that he sent a letter of thanks to the workers who build a tourist resort in the Winson region, which some South Korean media have mentioned that he might be there.

Last week, China sent a North Korea team of medical experts to advise on Kim, said three people familiar with the situation.

The CNN channel quoted a US official as saying that Washington was "studying information" stating that Kim Jong-un was "in a very serious condition as a result of the surgery". On Thursday, however, US President Donald Trump considered that the information about Kim's deteriorating health was "probably wrong", but he declined to say whether he was in contact with North Korean officials.