The half-brother of North Korean leader Kim Jong-un has been killed in Malaysia, South Korean and Malaysian sources say.
Kim Jong-nam, 45, is said to have been targeted at the airport in Kuala Lumpur, the capital.
A source close to the Malaysian PM's office told the BBC that Mr Kim was killed in the city, saying 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 the Reuters news agency that a North Korean man who died in transit to hospital from the airport on Monday was Mr Kim.
According to a report from TV Chosun, a cable television network in South Korea, Mr Kim was poisoned at the airport by two women, believed to be North Korean operatives.
A UK source with close ties to the Kim family told the BBC that poison had been involved in the death.
In 2001, Mr Kim 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 favour with his father over the incident.
Bypassed in favour 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.
He was quoted by Japanese media in 2011 as saying he opposed "dynastic succession".
He was also quoted in a 2012 book 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.
Mr Kim 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 organise a hit-and-run accident targeting him.