A highly toxic chemical was used in the death of North Korean leader Kim Jong-un's half brother last week, tests have shown.

Swabs taken from his face revealed that Kim Jong-nam had been sprayed with VX nerve agent - classified by the United Nations as a weapon of mass destruction.

Malaysian police announced on Friday that tests on the eyes and face of a North Korean national had been conducted.

Kim, 45, died shortly after appearing to be attacked by two women at Kuala Lumpur airport while he was waiting to board a flight to Macau.

The substance reported to have been found on his person is also known as S-2 Diisoprophylaminoethyl methylphosphonothiolate.

Specialists are now in the process of decontaminating Kuala Lumpur airport for the next 11 days.

Autopsies have been conducted on Kim's body Credit: AP

Malaysian police strongly suspect that North Korea is behind the killing, though have not directly blamed them.

So far, officers have identified a total of eight North Koreans suspected of being linked to Kim's death. One is currently being held in custody.

On Friday, Malaysian police revealed that one of the women who had attacked Kim was suffering from side-effects brought on by handling the chemical agent, including vomiting.

North Korea, meanwhile, has blamed Malaysia for the death of Kim - once believed to be the likely successor to Kim Jong-il.

The east Asian country said that responsibility for his death laid with Malaysia as he had died on their territory.

The lead Malaysian investigator working on the case reject accusations of government involvement leveled at the country by North Korea's ambassador who he said "continues to be delusional and spool lies and accusations against our government."

North Korea has also accused Malaysia of adopting an "unfriendly attitude" and collaborating with South Korea, who also believe their neighbour had Kim assassinated.