The two women accused of killing the half-brother of North Korea's leader with a nerve agent in a Kuala Lumpur airport terminal will be charged with murder, Malaysia's attorney general said on Tuesday.

Police allege the women smeared VX nerve agent - a chemical on a UN list of weapons of mass destruction - on Kim Jong-nam's face in an assault recorded on airport security cameras on February 13.

Attorney General Mohamed Apandi Ali said Indonesian Siti Aisyah and Vietnamese Doan Thi Huong will be charged on Wednesday and face a mandatory death sentence if convicted.

"They will be charged in court under Section 302 [murder] of the penal code," Mohamed said.

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Indonesia's deputy ambassador to Malaysia, Andriano Erwin, said on Saturday that Aisyah said she was paid $90 and repeated her previous claim that she was duped into the plot, thinking she was taking part in a prank. Huong told Vietnamese officials a similar story.

Police have said the women knew what they were doing when they attacked Kim and were instructed to wash their hands afterwards. But regardless of whether they did or not know of the murder plot, both appear to have been viewed as expendable by whoever gave them the VX.

Authorities have not said how the women were able to apply the nerve agent to Kim's face and also avoid becoming ill themselves.

Two other suspects have been arrested: a Malaysian who is out on bail and a North Korean who remains in custody.

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Asked if the North Korean would be charged, Apandi said it depends on the outcome of the investigation.

Authorities also are seeking another seven North Korean suspects, four of whom fled the country the day of Kim's death and are believed to be back in North Korea.

North Korea sent a high-level delegation to Malaysia to seek the return of the body.

The delegation includes Ri Tong-il, former North Korean deputy ambassador to the United Nations. He told reporters on Tuesday outside the North Korean Embassy in Kuala Lumpur that the diplomats were in Malaysia to seek the retrieval of the body and the release of the North Korean arrested in the case.

Ri said the delegation also seeks the "development of friendly relationships" between North Korea and Malaysia.

Al Jazeera's Florence Looi, reporting from Kuala Lumpur, said the North Koreans were upset that an autopsy was carried out on Kim without their permission. "They want the body returned immediately to the embassy," she said.

South Korean politicians said on Monday that the country's National Intelligence Service told them that four of the North Koreans identified as suspects are from the Ministry of State Security, the North's spy agency.

Two other suspects are affiliated with Pyongyang's Foreign Ministry, one of the politicians alleged.

Deadly nerve agent

Kim's killing took place amid crowds of travellers at Kuala Lumpur's airport and appeared to be a well-planned hit. Malaysian authorities say North Koreans put the deadly nerve agent VX on the hands of Aisyah and Huong, who then placed the toxin on Kim's face.

Malaysia has not directly accused North Korea of having masterminded the killing.

North Korea has repeatedly criticised Malaysia's investigation and has not acknowledged the victim's identity.

Police last week identified the substance as the banned chemical weapon VX nerve agent, and Malaysia's health minister said on Sunday the dose was so high it caused "very serious paralysis" and killed him within 20 minutes.