Mr Kim Jong Nam, the estranged half-brother of North Korea's leader, was killed by poison at Kuala Lumpur's airport on Monday, according to South Korean news reports citing government sources.
Two unidentified women, believed to be North Korean agents, attacked Mr Kim with poisoned needles before fleeing in a taxi, South Korean cable channel TV Chosun reported yesterday, citing a government source.
Mr Kim was waiting at the airport's Terminal 2 to board a flight to Macau, according to Malaysian police.
A police report obtained by The Straits Times showed that a Korean man accompanied by an airport staff member approached a police officer at about 9am, saying that he was attacked with a dangerous liquid by two unknown women.
The police have identified the man as Kim Chol, 46, from Pyongyang, based on his passport. A police statement said he sought medical aid at the airport's customer service and died en route to hospital.
"An investigation is in progress and a post-mortem examination request has been made, to ascertain the cause of death," Inspector-General of Police Khalid Abu Bakar said.
South Korea's presidential Blue House, as well as the Unification Ministry, said they have "nothing to confirm" regarding the news reports.
There is no official confirmation yet if Mr Kim Chol and Mr Kim Jong Nam are the same person.
Mr Kim Jong Nam, 45, often pictured wearing a cap, was the eldest son of late North Korean leader Kim Jong Il and was once groomed to be his successor. But he fell out of favour and was exiled to Macau after he was arrested in Tokyo in 2001 for entering Japan on a fake passport.
Jong Un, his younger brother from another mother, was named the new leader after their father died in late 2011.
If confirmed, Mr Kim's death would be the most high-profile one since the execution of his uncle Jang Song Thaek in December 2013. The two are said to have been close.
In January 2012, Mr Kim reportedly fled Macau out of fear of his life, as his home was exposed to North Korean agents and the media.
South Korea's mainstream newspaper Chosun Ilbo said he later settled down in Singapore, choosing the island state for ease of travel to Europe, where his son Han Sol was studying. Other reports said Mr Kim lived in Singapore, Malaysia and Indonesia, and that he had lovers in Singapore and Malaysia.
Mr Kim was known to lead a life of luxury outside his country. He was known to frequent five-star hotels and expensive restaurants. There were rumours he was protected by China, which was grooming him to take over if the Kim Jong Un regime were to collapse.
