PYONGYANG, May 2 (CNN) - North Korean state-run media is reporting that Kim Jong Un made an appearance at a May Day celebration, which would be his first public appearance in about three weeks.

"Supreme Leader Kim Jong Un Cuts Tape For Completion Of Sunchon Phosphatic Fertilizer Factory," the Korean Central News Agency (KCNA) reported.

KCNA says there was a "completion ceremony of the factory" on Friday, "the international holiday of the working people of the whole world."

KCNA released a still photograph purportedly showing Kim at the ceremony. The picture shows him cutting a red ribbon, with his sister Kim Yo-jong standing behind him. CNN cannot independently verify the authenticity of the photograph or the date it was shot.

Questions were raised about Kim's well-being after he missed the celebration of his grandfather's birthday on April 15. He had been seen four days before that at a politburo meeting, according to North Korean state media, KCNA.

North Korean state newspaper Rodong Sinmun said Sunday that Kim sent thanks to workers who helped in remodeling the city of Samjiyon.

CNN cannot independently confirm the authenticity of Sunday's report and whether the note of thanks came directly from the leader.

The same newspaper said Friday that Kim had "sent thanks" to exemplary party members for their work promoting party policy. The article did not give details for when or how his sentiments were expressed.

It is not the first time North Korean media has reported on Kim's activities since news of his potential health issues emerged.
US President Donald Trump declined to comment on the May Day appearance report.

"I'd rather not comment on it yet, Kim Jong Un. We'll have something to say about it at the appropriate time," he told reporters before departing the White House for Camp David.

On Sunday, South Korean presidential adviser Moon Chung-in told CNN that the North Korean leader was "alive and well" despite speculation about his well-being.

The adviser to South Korean President Moon Jae-in said Kim had been staying in the Wonsan area on the country's east coast since April 13, adding: "No suspicious movements have so far been detected."

A website specializing in North Korean affairs published satellite images on Saturday that researchers said showed a train, "probably belonging to Kim Jong Un," which had been parked at a railway station serving Kim's luxurious Wonsan compound on the country's eastern coast since at least April 21.