North Korean leader Kim Jong-un is in critical condition after surgery, CNN said Tuesday, citing a US official with direct knowledge of the matter.

Earlier on Monday, a South Korean online media outlet specializing in North Korea news reported Kim underwent a cardiovascular procedure and was in recovery. 

Kim was not present at the celebration of the birthday of his grandfather Kim Il-sung on April 15, fueling speculation about his health. It was the first time he had been absent from the event since he came to power in 2012.