The final suspect on trial over the alleged assassination of the North Korean leader's half brother using VX nerve agent has been sentenced to three years and four months in jail after pleading guilty to a lesser charge.

Duan Thi Huong (30) from Vietnam had been facing the possible death penalty if found guilty of the murder of Kim Jong Nam at Kuala Lumpur International Airport in February 2017.

On Monday in court in Malaysia she pleaded guilty to voluntarily causing hurt by a dangerous weapon, which carries a jail sentence of a maximum of 10 years.

Her defence argued that she was "naive and gullible" and had been manipulated to carry out the crime by four North Koreans, who they claim are the real assassins and are still at large.

Last month, her co-accused Siti Aisyah (27) from Indonesia was released after the attorney-general agreed to drop the charges against her following petitioning from the Indonesian government.

Huong's appeal for similar leniency was rejected three days later but her legal team and Vietnamese officials have continued to lobby on her behalf.

Mr Kim's face was smeared with VX, a banned nerve agent developed as a chemical weapon on February 13th, 2017.

He died before he could reach hospital.

Throughout the trial, prosecutors have claimed both Siti Aiysah and Doan Thi Huong were trained assassins and knew they had to wash their hands within 15 minutes to avoid being hurt by the VX.

A Hazmat team conducts checks inside Kuala Lumpur Internatinal Airport in Malaysia in February 2017 | Image: NurPhoto/SIPA USA/PA Images

Wan Shaharuddin Wan Ladin likened the "assassination" to something seen "in a James Bond movie".

Their defence lawyers argued the women did not know they were poisoning Mr Kim but believed they were playing pranks for a reality TV show, having previously been paid for playing similar tricks at shopping malls and airports.

They claim they were unwitting pawns in a politically motivated murder.

CCTV from the airport shows a woman identified as Huong running up behind Mr Kim and rubbing something on his face before walking away.

Sentencing her on Monday. the judge said she was "a lucky person because from the original charge of murder which carries a mandatory sentence of death, the prosecution has offered you an alternative charge".

The accused replied: "Thank you very much."

The judge said the sentence would run from when she was arrested on February 15th 2017.Her defence team told journalists she would be released in May.

Once North Korea's heir apparent, Kim Jong Nam was living in exile in Macau, and had criticised his family's dynastic rule.

The court heard that he was carrying a dozen vials of a potential antidote for lethal nerve agent VX in his sling bag on the day he was poisoned and six months earlier had told a friend he feared for his life.

The murder using a banned chemical weapon in a packed airport unravelled the once close ties between Malaysia and North Korea.

Malaysia was forced to return Kim Jong Nam's body and allow the return home of three North Korean men wanted for questioning and hiding in the Kuala Lumpur embassy, in exchange for the release of nine Malaysians stuck in Pyongyang.

North Korea has denied accusations by South Korean and US officials that Kim Jong Un's regime was behind the killing.