In an escalating row over the killing of Kim Jong-nam, the half-brother of North Korean leader Kim Jong-un, Malaysia has stepped up diplomatic measures against North Korea.

On February 13, Kim Jong-nam died in mysterious circumstances at an airport in Kuala Lumpur.

Malaysian police believe he was poisoned.

Malaysia has recalled its ambassador from the North Korea and has summoned the North Korean ambassador “to seek an explanation”.

Malaysian police say they are now looking for four North Korean suspects.

Meanwhile, a video which apparently shows CCTV footage of the attack on Kim Jong-nam has surfaced and aired on Japan’s TV.

Despite widespread speculation that North Korea was behind the killing, there has been no definitive evidence and Pyongyang has not issued an official statement yet.

On February 17, North Korean ambassador Kang Chol accused the government in Kuala Lumpur of colluding with “hostile forces”, saying that Malaysia had “something to conceal”.

South Korea has accused North Korea of orchestrating the incident, saying on February 20 it was evidence of North Korean “terrorism getting bolder”.

Malaysia was one of very few countries to maintain diplomatic relations with North Korea, but this killing has strained ties.

It has refused to accede to North Korean demands to release Kim’s body into their custody without an autopsy.

That apparently prompted the comments on February 17 by North Korea’s ambassador to Malaysia – which provoked an angry response from the Malaysian foreign ministry.

It said his accusation was “baseless”, adding that it was their responsibility to conduct an investigation as Kim Jong-nam had died on Malaysian soil.

Malaysian authorities are now waiting for the results of its autopsy. Kang Chol said his country would reject the result as it was done without the presence of its representatives.

Malaysia has also refused to release Kim Jong-nam’s body, saying it needs to conduct DNA testing first.

Police are now seeking samples from family members. Kim Jong-nam is believed to have family living in Beijing and Macau.

Malaysian police have said that if there is no claim by next of kin and once they exhaust all avenues for DNA collection, they will hand the body over to the North Korean embassy.

Kim Jong-nam is believed to have been attacked in the Kuala Lumpur airport departure hall on Monday by two women, using some form of chemical.

Japan’s Fuji TV has aired grainy CCTV footage showing a man resembling Kim Jong-nam approached by a woman at the airport.

Another woman then quickly lunges from behind and wipes his face with a cloth. She is seen wearing a white top emblazoned with the letters “LOL”.

The man is then seen seeking assistance from airport staff while gesturing at his face, and is escorted to a room.

Two women, one Indonesian and one Vietnamese, were among the first to be arrested. The Indonesian, named as Siti Aisyah, is said to have told Malaysian police she had been paid to perform what she thought was a prank.

Police have also detained one North Korean suspect, Ri Jong-chol, and said they are looking for four more men, who may have already left the country.

The men have been named as Ri Ji-hyon, 33; Hong Song-hac, 34; O Jong-gil, 55, and Ri Jae-nam, 57.

Kim Jong-nam was the first-born son of former North Korean leader Kim Jong-il, who died in 2011.

He was largely estranged from his family, after being passed over for the North Korean leadership in favor of his youngest half-brother.

Kim Jong-nam went into exile in the early 2000s, spending most of his time in Macau, mainland China and Singapore.