Police are seeking to record a statement from a senior official attached to the North Korean embassy in Malaysia to facilitate investigations into the murder of Kim Jong-nam.

However, inspector-general of police Khalid Abu Bakar declined to confirm if the official, who the police chief said held the rank of second secretary, was a suspect.

Asked if the official was a suspect, he replied: "We would call them first."

He said police have also requested to record a statement from a staff of Air Koryo, the North Korean national airline.

"We have written to the North Korean embassy to allow us to interview both of them.

"We hope the embassy will cooperate with us and allow us to interview them quickly. If not, we will compel them (to do so)," Khalid told a press conference in Kuala Lumpur today.

Failure to cooperate, Khalid said, would result in the police issuing warrants of arrest against the two individuals.

While three suspects, including two women, remain in custody, Khalid said police "strongly believe" that four other suspects who fled Malaysia on Feb 13, the day of the attack, had arrived in Pyongyang.

"We believe the fifth suspect is still in the country," he added

Jong-nam, the estranged half-brother of North Korean leader Kim Jong-un, was killed at the Kuala Lumpur International Airport (KLIA 2) while he was preparing to board a flight to Macau.

'North Korea uncooperative'

Meanwhile, Khalid accused North Korea of being "uncooperative" and had yet to offer any assistance, including contacting Jong-nam's family members to identify the body.

"We have our ways (but) we won't tell you," he replied when quizzed if the police had other ways of contacting the deceased's family.

On reports that claim Jong-nam's son Kim Han-sol is in Malaysia, Khalid described this as a rumour.

The police chief also maintained that Malaysian authorities have consistently referred to Jong-nam as Kim Chol, as per the name on the passport in his possession.

At the same time, he said, police have requested access to Jong-nam's family members as their DNA is needed to confirm his identity.

"Everyone is saying he is Kim Jong-nam. So we need the DNA to prove that he is Kim Jong-nam," Khalid added.