A man claiming to be the son of murdered Kim Jong-Nam has said in a video posted online that he is lying low with his mother and sister after the killing.

The footage was posted by the Cheollima Civil Defense group, which said the governments of the Netherlands, China, the US and a fourth unnamed country provided emergency humanitarian assistance to protect the family.

The man, identified by South Korea's National Intelligence Service as Kim Han-Sol, shows a North Korean passport to the camera in the video and thanks an unnamed person or group for their support.

Speaking in English, he says: "I'm currently with my mother and my sister... we hope this gets better soon."

Mr Kim, 21, is the son of Kim Jong-Nam's second wife, who had been living in the Chinese territory of Macau under Beijing's protection after the family went into exile several years ago.

Kim Jong-Nam, the estranged half brother of North Korean leader Kim Jong-Un, was killed at Kuala Lumpur International Airport on 13 February after two women wiped VX nerve agent on his face.

The Cheollima Civil Defense group said it has responded to an emergency request by Mr Kim's family for "extraction and protection".

It thanked the Netherlands ambassador to North and South Korea, Lody Embrechts, for his "timely and strong response".

Mr Embrechts, who is based in South Korea, did not comment on the statement.

The group said: "The three family members were met quickly and relocated to safety. We have in the past addressed other urgent needs for protection."

South Korean intelligence officers have claimed Kim Jong-Un issued standing orders for his elder half-brother to be killed.

It comes after Malaysia's prime minister said relatives of the murdered man may be too scared to come forward to provide DNA samples.

Najib Razik said his country was trying to negotiate with Pyongyang after relations have deteriorated over the investigation into the killing.

He said: "This is (a) sensitive matter, best conducted in secrecy. Maybe they are scared to come forward."

On Tuesday, North Korea announced it was blocking all Malaysians from leaving the country until it had reached a "fair settlement" of the case.

Malaysia responded by barring North Koreans from leaving its soil.