North Korean leader Kim Jong-un is “alive and well”, an advisor to South Korean President Moon Jae-in told CNN on Sunday. On April 21, the South Korean government had said it cannot confirm reports that Kim is in danger following a major surgery.

“Our government position is firm,” Moon Chung-in, the top foreign policy adviser to South Korean President Moon Jae-in, said. “Kim Jong-un is alive and well. He has been staying in the Wonsan area [of North Korea] since April 13. No suspicious movements have so far been detected.”

Doubts were raised about Kim’s well-being after he missed the celebration of his grandfather’s birthday on April 15. On April 21, Daily NK, an online newspaper based in South Korea that focuses on North Korea, said that Kim had undergone a heart surgery at Hyangsan Hospital due to “a number of factors, including his obesity, prolific smoking habits, and overwork”.

South Korea’s Unification Ministry had said that it was the first instance that Kim had failed to attend the ceremony at the palace to honour his grandfather since he came to power in 2012.

On Sunday, North Korea’s state newspaper Rodong Sinmun said Kim has thanked workers who helped in remodeling the city of Samjiyon in North Korea, CNN reported. However, the news network added that it could not independently verify the authenticity of the newspaper’s claims.

Getting inputs from North Korea has always been very difficult as the nuclear-armed country tightly controls any information surrounding its leader. Kim’s absence from state media had triggered speculations about his health earlier too. In 2014, he was not in the public eye for nearly six weeks. Days later, South Korea’s spy agency said he had a cyst removed from his ankle.