Malaysian police have detained a third suspect in connection with the murder of Kim Jong-nam, the half-brother of North Korean leader Kim Jong-un.

A police spokesman said the man is the boyfriend of a woman arrested earlier in the day.

She was holding an Indonesian passport.

Yesterday,a female suspect with Vietnamese travel documents was arrested

She is due to be brought to a Kuala Lumpur court later today.

South Korean officials earlier cited their spy agency as saying it suspected two female North Korean agents had murdered Kim Jong-nam.

US government sources also said they believed North Korean assassins were responsible. 

A Malaysian government source confirmed that the first suspect detained was the same woman whose image was captured by close circuit television footage and published by media.

The grainy picture showed her wearing a white shirt with the letters "LOL" on the front.

She was arrested at Kuala Lumpur International Airport, two days after Kim Jong-nam was exposed to with what is believed to be a fast-acting poison.

Police said she was alone when she was picked up, and held travel documents that were issued in Vietnam.

Deputy Inspector-General Noor Rashid Ibrahim said: "Police are looking for a few others, all foreigners."

However, he declined to say what nationalities and genders the other suspects are.

As yet there has been no mention of Kim Jong-nam's death in North Korean state media.

Last night Kim Jong-un visited the Kumsusan Palace of the Sunto mark the birthday of his father, the late leader Kim Jong-il,who died in 2011.

South Korea's intelligence agency told officials in Seoul, that the young and unpredictable North Korean leader had issued a "standing order" for his elder half-brother's assassination, and that there had been a failed attempt in 2012.

Malaysian police said Kim Jong-nam had been at the airport's budget terminal to catch a flight to Macau on Monday when someone grabbed or held his face from behind, after which he felt dizzy and sought help at an information desk.

Malaysian authorities have rebuffed North Korean officials efforts to stop a post-mortem examination being carried out on his body.