"Comrade Kim Jong-un sent appreciation to workers earnestly and wholeheartedly supporting in furnishing Samjiyon," South Korea's Yonhap News Agency quoted Pyongyang state radio as saying in a report on Sunday.
Samjiyon is located at the foot of Mount Paekdu, the highest peak on the Korean Peninsula, known to be the birthplace of Kim's late father and former leader Kim Jong-il.
The report, however, did not provide other details that could provide clues about Kim Jong-un's whereabouts or health conditions.
Other state media, including the Korean Central News Agency and the Rodong Sinmun, did not report on his public activities either, nor did they provide any photos of the leader.
Kim Jong-un has been out of public view since he was last seen on April 11 chairing a major party meeting, reports Yonhap News Agency.
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He skipped an important annual trip to the Kumsusan Palace of the Sun on the occasion of the April 15 birthday of the late state founder and his grandfather, Kim Il-sung, sparking rumours over what was behind his unprecedented no-show at the mausoleum.
Last week, CNN intensified speculation about his health by reporting earlier this week that the US was looking into intelligence that Kim Jong-un is "in grave danger" after surgery, but Seoul and Washington officials have disputed the report.
It is not rare for Kim to disappear from the public view but whenever it happens, rumours spread about his health, with most of the cases having proved to be false.
He re-emerged after about a three-week absence by visiting the mausoleum to mark his late father's birthday on February 15.