Malaysia decontaminating airport after revealing North Korean agents 'assassinated Kim Jong-nam with highly-toxic VX nerve agent'

Mr Abu Bakar said that experts were beginning to decontaminate the budget terminal where Mr Kim was killed as well as other sites that the suspected killers had visited. 

It is not known whether the VX could linger in the terminal or have delayed long-term effects on people who may have been exposed to it. 

The nerve agent is considered a weapon of mass destruction and much of the world has committed to destroying its stockpiles of the deadly agent. But North Korea retains one of the world’s largest chemical arsenals and has ample supplies of VX.

It is not clear if the alleged North Korean agents were able to smuggle the deadly weapon into Malaysia or if they somehow assembled it themselves inside the country. Both possibilities are alarming for the Malaysian security services.   

The two women accused of killing Mr Kim both seem to be in good health despite their contact with VX, although one of them began to vomit after her arrest, according to police. 

Dr Bruce Goldberger, a toxicologist at the University of Florida, said it was possible that the two women had been given an antidote ahead of carrying out the killing, which would have spared them the worst effects of the toxin. 

"I'm intrigued that these two alleged assassins suffered no ill effect from exposure to VX," Dr Goldberger said. "It is possible that both of these women were given the antidote."

VX was first developed in Britain in the 1950s by scientists doing research on pesticides. Saddam Hussein is believed to have used it against Kurdish opponents in the late 1980s while a Japanese death cult was able to kill one person in the mid-1990s by attacking them with VX.

The same cult, Aum Shinrikyo, used sarin gas - a cousin of VX - to carry out an attack on the Tokyo subway system in 1995. The attack killed 12 people and badly injured dozens of others. 

North Korea has denied responsibility for the murder, saying that the allegations made by Malaysian investigators were fabrications made on behalf of South Korea. 

Malaysia has not formally accused the North Korean state of the assassination it has said that four North Korean men provided the two women with the deadly nerve agent. All four fled Malaysia shortly after Mr Kim’s death, police said. 

North Korea meanwhile lashed out at China, one of the isolated state’s few allies, saying that Beijing was “dancing to the tune of the US” after it halted coal imports from North Korea. 

China made the decision over the weekend in protest at a North Korean missile test, prompting Pyongyang to strike out at China in terms it usually reserves for South Korea.     

While not naming China directly, North Korean state media referred to “a neighbouring country, which often claims itself to be a ‘friendly neighbour.’”

China is under pressure from the Trump administration to do more to rein in North Korea but its position on its rogue neighbour is complicated. 

While it looks for stability in North Korea and finds Pyongyang to be an occasionally useful foil, Beijing also regularly appears to be exasperated by its neighbour’s erratic behaviour. 

Fatal in minutes

VX is tasteless and odourless, and is outlawed under the Chemical Weapons Convention, except for "research, medical or pharmaceutical purposes". It can be manufactured as a liquid, cream or aerosol.

Experts say it has no commercial uses.

"This is not something you make in a kitchen lab. This is something that is made in a very sophisticated chemicals weapons lab," said Bruce Bennet, a senior defense researcher at the California-based RAND Corporation.

North Korea is believed to have the world's third-largest stockpile of chemical weapons, according to the Nuclear Threat Initiative project, which analyses weapons of mass destruction.

South Korean analysts have identified sarin and VX as the focus of the North Korean chemical weapons programme.

VX in liquid form can be absorbed into the body through skin or eye contact and does not evaporate easily.

After giddiness and nausea, exposure to VX quickly progresses to convulsions and respiratory failure before death, according to the U.S. Centers for Disease Control and Prevention (CDC).

Prior to death, a victim would likely have convulsions, seizures, loss of consciousness and paralysis.

Malaysian authorities on Thursday requested Interpol to put an alert out to apprehend four North Korean suspects who are believed to have fled from Malaysia on the day of the attack.

They also want to question the second secretary at the North Korean embassy, who is believed to be 'hiding' in Pyongyang's embassy in Kuala Lumpur along with another North Korean suspect.

The murder has strained relations between North Korea, which has been increasingly isolated in response to its nuclear and missile programmes, and Malaysia.

North Korea has said Malaysia should be held responsible for the killing of one of its citizens, though it has not acknowledged that the victim is the half brother of North Korean leader Kim Jong Un.

Malaysia has recalled its ambassador from Pyongyang for consultations.