A South Korean government source told Reuters that Kim Jong-nam is believed to have been killed after being attacked by two unidentified female agents with "poisoned needles."
The suspects fled the scene and Malaysian police suspect North Korea was behind the killing.
Mr Kim went into hiding in Malaysia after the execution in December 2013 of his uncle, Jang Song-thaek, the once-powerful uncle of the current leader.
The eldest son of Kim Jong-il, he survived an assassination attempt in Macau in 2011.
While he was widely seen as heir to the hermit kingdom`s throne, he fell out of favour after being detained while trying to enter Japan on a forged passport along with two women and a child.
He said he wanted to visit Disneyland.
If confirmed, Kim`s case would mark the most high-profile death under the Kim Jong-un regime since the execution of Jang Song-thaek.
Kim Jong-nam was born from his father`s non-marital relationship with Sung Hae-rim, a South Korean-born actress who died in Moscow.
Kim Jong-un`s half-brother `assassinated with poisoned needles`
14 February 2017
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North Korean leader Kim Jong-un`s brother has been assassinated at an airport in Malaysia, according to the South Korean news agency Yonhap News.
