North Korean leader Kim Jong-un’s half-brother was an informant for the US Central Intelligence Agency before he was assassinated in Malaysia, it has been claimed.

The report of a “nexus” between the CIA and Kim Jong-nam, 45, surfaced in the Wall Street Journal on Monday, citing an unnamed “person knowledgeable about the matter.”

However, the claim was first reported last week in The Times, based on a new book by Anna Fifield, a Washington Post journalist, which alleges that Kim was not only a CIA informant but that he laundered counterfeit money through casinos and associated with gangsters.

The book sheds new light on the possible reasons for Kim’s gruesome murder in February 2017 in Kuala Lumpur airport, when he was smeared with lethal VX agent by two women who thought they were taking part in a reality TV prank show.

The US and South Korea have accused the North Korean regime of orchestrating the audacious assassination, although Pyongyang denies the accusation.

Donald Trump said he would not have allowed US intelligence to use Kim Jong-un's half-brother as an asset.

Asked about the CIA's links to Kim Jong-nam, Mr Trump said: "I don't know about that... I know that the relationship is such that that wouldn't happen under my auspices."