Did Kim Jong-Un have his brother killed because he feared he was part of a US-backed coup?

Kim Jong Nam, the estranged brother of North Korean leader Kim Jong Un, at the Seoul Railway Station. Photo / AP

Kim Jong-Nam, the half-brother of North Korean dictator Kim Jong-Un, reportedly met an American spy in Malaysia just four days before he was poisoned.

CCTV purports to shows the 45-year-old, who was assassinated at Kuala Lumpur airport, with a "middle-aged Korean-American" man in a hotel lift at the resort island of Langkawi in northern Malaysia on February 9.

Kim, who had allegedly met the contact several times before, stayed in a hotel suite with him for two hours, the Daily Mail reports.

His computer showed a record of a USB memory stick being inserted into it, which may have been used to pass on crucial information to the suspected US agent, the Asian news outlet reported.

Malaysian authorities speculated that North Korea's secret police became aware of the meeting and decided to silence Kim.

According to the report, Kim arrived alone at Kuala Lumpur without telling anyone on February 6 from Macau, where he was living in exile with his family.

He returned from Langkawi to Kuala Lumpur on the evening of February 12.

A day later, he was poisoned at Kuala Lumpur International Airport in a brazen Cold War-style assassination using a lethal nerve agent banned by the UN as a weapon of mass destruction.

There have been claims that Kim Jong-Un had his brother killed because he feared he was part of a US-backed coup.

The US and even China may want to groom Kim Jong-Nam in an effort to remove his brother from power, Business Insider reported.

The North Korean dictator has caused global concern with his ballistic missile demonstrations and reported violent purges of top officials.

At 33, he could rule North Korea for up to five decades with a leadership that is openly hostile to the US.

North Korea also has little contact with China. Kim has never visited Beijing just like Chinese President Xi Jinping has never been to Pyongyang.

Kim has also had top officials with ties to China brutally killed with packs of dogs or anti-aircraft guns, according to reports.

North Korea executed five senior security officials in February because they made false reports that "enraged" Kim Jong Un, South Korea's spy agency said.

North Korean leader Kim Jong Un watches the test launch of a solid-fuel 'Pukguksong'. Photo / AP

With little influence over Jong-un, Chinese diplomats could have persuaded generals and senior officials in North Korea to back Kim Jong-Nam in a coup, Business Insider speculated.

The assassin used the world's deadliest chemical weapon that needs just a drop to kill someone, it has emerged.

CCTV footage of Jong-Nam's final minutes shows one female assassin wiping a fast-acting poison on his face from behind.

Other shots show him stumbling, wiping his face, and seeking help from people while gesturing to his eyes before being escorted to a clinic.

He later slumped in a chair after he suffered a seizure and died on February 13.

Traces of VX, considered one of the five most deadly chemical weapons of war that produces a feeling of drowning before death, were detected on swabs of the dead man's face and eyes.

Kim had traces of VX, which is classified as a weapon of mass destruction by the United Nations, on his face and his eyes after being targeted at Kuala Lumpur International Airport.

Experts say only a minute amount of the banned nerve agent is needed to kill.

Kim Jong Un waves during a military parade in Pyongyang, North Korea. Photo / AP

Police said one of two women suspected of the killing was vomiting profusely afterwards and experts says that his murderers were probably wearing thin gloves and washed their hands afterwards to avoid killing themselves.

North Korean dictator Kim Jong-un is believed to have a large stockpile of the poison among a terrifying arsenal of up to 5000-tonnes of chemical weapons.

South Korea has blamed Pyongyang for Kim's death, but the North has rejected those claims and has never confirmed the identity of the victim, who was carrying a passport bearing the name of Kim Chol when he was attacked.

Pyongyang had denounced Malaysia's investigation as an attempt to smear the secretive regime, insisting that Kim most likely died of a heart attack.

Two women - Indonesian Siti Aisyah, 25, and Doan Thi Huong, 28, from Vietnam - have been arrested and charged with the murder.

Hazmat crews investigate the check in kiosk machines at Kuala Lumpur International Airport. Photo / AP

They could be hanged if found guilty.

Aishah has already admitted that she worked in a massage parlour, while Huong has told police that she earned money for her family back in Vietnam by escorting men in night clubs and being paid well for her services.

They told officials from their embassies in Malaysia that they believed the entire operation was a harmless prank for a reality show.

Malaysian police say the attackers knew what they were doing and had been trained to go immediately to the bathroom and clean their hands.

Kim Jong Nam, who had been living in the Chinese territory of Macau under Beijing's protection, had spoken out publicly against his family's dynastic control of the isolated, nuclear-armed North Korea.