Kim Jong-un’s half-brother, Kim Jong-nam, has been killed in Malaysia, South Korean and Malaysian sources say.
The 45-year-old is said to have been targeted at the airport in Kuala Lumpur.
According to local media, his body was now undergoing an autopsy.
Kim Jong-nam was the eldest son of former North Korean leader Kim Jong-il.
Malaysian police have confirmed to Reuters that a North Korean man who died in transit to hospital from the airport on February 13 was Kim Jong-nam.
According to a report from TV Chosun, a cable TV network in South Korea, Kim Jong-nam was poisoned at the airport by two women, believed to be North Korean operatives.
In 2001, Kim Jong-nam was caught trying to enter Japan using a false passport. He told officials that he was planning to visit Tokyo Disneyland.
Once seen as a likely successor to Kim Jong-il, he was thought to have fallen out of favor with his father over the incident.
Bypassed in favor of his youngest half-brother for succession when their father died in 2011, Kim Jong-nam kept a low profile, spending most of his time overseas in Macau, Singapore and China.
Kim Jong-nam was quoted by Japanese media in 2011 as saying he opposed “dynastic succession”.
In a 2012 book, he was also quoted as saying he believed his younger half-brother lacked leadership qualities, the succession would not work and that North Korea was unstable and needed Chinese-style economic reform.
Kim Jong-nam was reportedly targeted for assassination in the past. A North Korean spy jailed by South Korea in 2012 was reported to have admitted trying to organize a hit-and-run accident targeting Kim Jong-nam.