A special train possibly belonging to North Korean leader Kim Jong Un was spotted this week at a resort town in the country, according to satellite images reviewed by a Washington-based North Korea monitoring project, amid conflicting reports about Kim's health and whereabouts.

The monitoring project, 38 North, said in its report on Saturday that the train was parked at the "leadership station" in Wonsan on April 21 and April 23. The station is reserved for the use of the Kim family, it said.

Though the group said it was probably Kim Jong Un's train, Reuters has not been able to confirm that independently, or whether he was in Wonsan.