Washington-based "38 North" North Korea research center said that satellite images it reviewed showed a special train likely to belong to North Korean leader Kim Jong Un at a resort within the country this week, amid conflicting reports about Kim's health and location.

The center explained in its report that the train, which is approximately 250 meters in length, was parked at the leadership station in Winson on April 21 and April 23, adding that the station is reserved for the Kim family.

The center said the train may belong to Kim, but this could not be independently confirmed or whether Kim was in Winson.

The center added that the presence of the train does not confirm the whereabouts of the North Korean leader, nor does it indicate anything about his health, but it strengthens reports that Kim is staying in an elite area on the east coast of the country.

Chinese medical team China
had sent a team to North Korea comprising health experts to advise on Kim's health, according to three people familiar with.

The voice of satellites reviewed by the "38 North" Center in Washington (Reuters)

There was speculation about Kim's health after his absence from the ceremony marking the birthday of his grandfather, Kim Il-sung, the founder of North Korea, on April 15.

The last time North Korea's official media spoke about Kim's whereabouts was when she reported on him as he chaired a meeting on April 11.

On Thursday, US President Donald Trump downplayed reports of Kim's illness and told reporters, "I think the report is incorrect," but he declined to say whether he was in contact with North Korean officials.

Trump has met Kim on three occasions in an attempt to persuade him to abandon North Korea's nuclear weapons program that threatens the United States and Korea's Asian neighbors. Although the talks have stalled, Trump still calls Kim a friend.